The Solomon Islands and Their Natives Part 45

(60) _Neritina porcata_ (Gould) _Hab._ St. Christoval, and Faro Island, Bougainville Straits, in streams.

(61) _Neritina variegata_ (Lesson) _Hab._ St. Christoval, Ugi; Simbo or Eddystone; Faro Island, Bougainville Straits; Choiseul Bay; in streams.

(62) _Neritina turtoni_ (Recluz) _Hab._ A stream in the Shortland Islands; streams in Guadalcanar; imbedded in a dark calcareous loam exposed in the banks of a large stream near to its mouth at Sulagina on the north coast of St. Christoval.

(63) _Neritina brevispina_ (Lamarck) _Hab._ Streams in Shortland, Treasury, and Ugi Islands. The specimens from Treasury Island were dest.i.tute of spines.

(64) _Neritina squarrosa_ (Recluz) _Hab._ Streams in Treasury Island.

(65) _Navicella sanguisuga_ (Reeve) _Hab._ Streams in Faro Island, Bougainville Straits.

(66) _Navicella suborbicularis_ (Sowerby) _Hab._ Guadalcanar, St.

Christoval, Ugi, Treasury and Faro Islands in Bougainville Straits.

(67) _Unio guppyi_ (nov. spec.) _Hab._ Streams in the Shortland Islands.

(68) _Cyrena_, spec. _Hab._ In the lower parts of streams and in mangrove swamps, Choiseul Bay. _Note._--This species is not referred to in the original paper.

_Descriptions of the new species and varieties_,[490] by Mr. E. Smith.

[490] The numbers refer to the plates in Mr. Smith's paper (Proc.

Zool. Soc., June 1885).

(2) _Helix_ (_Nanina_) _nitidissima._ (Plate x.x.xVI. figs. 1, 1 _b_.) Sh.e.l.l thin, transparent, very glossy, depressed, narrowly perforate, pale brownish horn-colour above, whitish towards the umbilicus, sculptured with very faint lines of growth. Whorls 4-5, slightly convex, impressed and marginate above at the suture; last whorl large, rounded at the periphery. Aperture obliquely lunate; peristome simple, thin, slightly thickened and reflexed partly over the perforation. Spire low, but very little raised above the last whorl, obtuse at the apex. Greatest diameter 14 millim., smallest 12; height 9.

(3) _Helix_ (_Nanina_) _solidiuscula._ (Plate x.x.xVI., figs. 2, 2 _b_.) Sh.e.l.l very narrowly perforate, depressed, somewhat solid, dark chestnut-brown and a little glossy above, more s.h.i.+ning and paler beneath, becoming almost white at the umbilical region; whorls 6, convex, separated by a deepish suture, and, with the exception of two or three at the apex which are smooth, sculptured with strong, close-set, arcuate, and oblique striae on the upper surface, crossed with a few more or less distinct spiral lines. Body-whorl rounded at the periphery, or sometimes with the faintest indication of an angle, convex, and only exhibiting fine lines of growth below.

Aperture obliquely semi-lunate; peristome simple, but, owing to the solidity of the sh.e.l.l, seeming slightly thickened, especially on the very oblique columellar margin, which is shortly reflexed above over the perforation. Spire depressed-conoid, having the least convex outlines and an obtuse apex. Greatest diameter 18 millim., smallest 16, height 12; aperture 8 long, 4 wide.

This species is well distinguished by its comparative solidity and strong sculpture on the upper surface.

(4) _Helix_ (_Corasia_) _tricolor_ (Pfeiffer). (Plate x.x.xVI., figs.

3, 3 _b_.) A specimen obtained on the north coast of the same island of St. Christoval, by Mr. Guppy, is worthy of special mention, and may be termed var. _picta_, on account of the undulating reddish-brown stripes which ornament both the upper and lower surfaces.

A similar example was also collected by Dr. A. Corrie and presented to the Museum. The markings on these two sh.e.l.ls are very striking and distinctly visible within the aperture.

(11) _Helix_ (_Geotrochus_) _guppyi._ (Plate x.x.xVI. fig. 4.) Sh.e.l.l elevately conical, thin, pale yellow, ornamented with conspicuous nearly black or black-brown spiral bands, one above and one below the sutures of the upper whorls, and three upon the last, one sutural, the second peripheral, and the third basal. Volutions 6, rather slowly enlarging, a little convex, sculptured with fine oblique striae of growth, not glossy. Three first whorls livid purplish, the last rather sharply angled at the middle, not descending in front, having the basal band broad around the almost concealed perforation, and obsolete within the aperture. The latter is oblique, somewhat narrowed and pouting in front, banded within with three almost black and two white bands, the central one of the former being squarely truncate at the end, only the lower corner of it touching the margin of the lip, which is pale oblique, receding, a little expanded and reflexed in front and at the columellar margin, the upper end of which is spread over and nearly conceals the small umbilicus. Height 22 millim., greatest diameter 19, smallest 16.

This species is remarkable for the striking contrast of its colour-bands and the angular character of the last whorl.

(12) _Helix_ (_Geotrochus_) _dampieri_, Angas, var. (Plate x.x.xVI.

fig. 5.) Sh.e.l.l imperforate, subglobose, conoid, light brown or fawn-colour, here and there minutely dotted with dark-grey specks, with a broad white band around the middle of the penultimate whorl and two upon the last, one above and the other below the middle, also a narrow white line revolving up the spire beneath the suture, and a dark brown zone surrounding the pale or yellowish umbilical region. Whorls 5, a little convex above, somewhat glossy, obliquely and very finely striated by the lines of growth, the last more or less concentrically striated beneath, shortly descending at the aperture which is white within. Lip a little thickened, edged with reddish brown, only slightly expanded on the right side, more dilated below, produced into a thin transparent callosity over the umbilical region, united above to the upper extremity of the peristome. Columellar margin oblique, white or partly tinged with reddish brown, thickened and terminating below within the edge of the lip. Height 19 millim., greatest diam. 22, smallest 19.

The specimens from the Solomon Islands are smaller than the type with which, through the kindness of Mr G. F. Angas, I have compared them. They also have the peristome brown, and the basal band is darker.

(14) _Helix_ (_Geotrochus_) _cleryi_, Recluz (Plate x.x.xVI. figs 6, 6 _b_). The specimens from Santa Anna (var. _meridionalis_ fig. 6 _b_) are smaller than the type, pale brown above, with a white thread-like line at the suture, and the acutely keeled periphery, paler beneath, especially towards the centre, and have the aperture particularly ac.u.minate at the termination of the keel.

The specimens from Simbo (var. _simboana_, fig. 6 _a_) are uniformly pale horn-colour, rather sharply carinate at the middle, and have the peristome white, considerably thickened and almost notched at the upper end of the columella, and the body-whorl is more contracted than in the typical form. The examples from Choiseul Bay, Shortland and Treasury Islands (var. _septentrionalis_, fig. 6) are all alike, of smaller dimensions than the normal form, thin pale brownish horn-colour, with rather more convex whorls than usual, the carina at the periphery being acute and thread-like as in the variety _simboana_.

Whether these several varieties should take specific rank is questionable, for, although there is considerable difference between the extreme forms even in the series of nearly one hundred specimens under examination, the gradual transition from one form to another is observable.

(16) _Helix_ (_Videna_) _sanctae annae._ (Plate x.x.xVI. figs. 7. 7 _b_.) Sh.e.l.l depressed-conoid, deeply umbilicated, very acutely keeled at the periphery, light brown, sometimes with a few radiating pale streaks on the upper surface, sculptured with oblique lines of growth. Whorls 5, rather slowly increasing, slightly convex, depressed and margined above the suture, last not descending, compressed above and below the keel, a little convex towards the umbilicus, which is moderately large. Aperture transverse, flesh-tinted within. Peristome simple, a little thickened along the basal margin, with the extremities united by a thin callus. Height 7 millim.; greatest diameter 17, smallest 15.

(25) _Cyclostoma_ (_Adelostoma_) _triste_, Tapparone Canefri, var.?

Dr. Tapparone Canefri has kindly compared specimens from these islands with his _C triste_, and is of opinion that they may be considered a variety of it; and observes that the New-Guinean form is a little smaller, its spire a little more slender, its surface more glossy, the colour redder, and the apex of the spire darker.

The sh.e.l.ls under examination are clothed with a very thin epidermis when in a fresh condition, exhibiting numerous very fine spiral thread-like lines, which entirely disappear in worn sh.e.l.ls and can easily be rubbed off with a brush. For several species having a similar epidermis and an incomplete peristome, Dr. Tapparone Canefri has proposed the subgenus _Adelostoma_.

(29) _Pupina solomonensis._(Plate x.x.xVI. fig. 9, 9 _a_.) Sh.e.l.l small and very like _P. difficilis_, Semper, and _P. keraudreni_, Vignard.

It is of a reddish tint, especially the body-whorl; consists of 5 whorls, which are the least convex and exhibit a pellucid line, frequently brown, immediately beneath the suture. Last whorl very obliquely descending behind, narrowed below, and flattened somewhat above the aperture. Columella thickened with callus, white, parted off from the whorl above by an oblique circ.u.mscribing red line, truncated rather low down. Outer lip slightly thickened and effuse, and a little paler than the rest of the whorl, produced somewhat at its junction with the body-whorl, which in consequence has the appearance of rising suddenly after an oblique descent. Length 7 millims., diam. 3?, aperture 2 long and wide.

(34) _Helicina solomonensis._ (Plate x.x.xVI. figs. 11, ll _b_.) Sh.e.l.l small, globose-conical, reddish or yellowish, pale at the apex.

Whorls 4--4, the least convex above, sculptured with lines of growth and fine spiral striae both on the upper and lower surfaces, very faintly margined above at the suture; last whorl rounded at the periphery, obsoletely angled near the junction of the outer lip and the least descending in front, so that the faint angulation is visible for a short distance above the sutural line. Aperture somewhat semicircular and oblique, small; peristome slightly expanded; umbilical callosity yellowish or pellucid whitish, defined towards the base of the columellar margin. Greatest width 4?

millim., smallest 4; height 3.

(44) _Melania subgradata._(Plate x.x.xVII. fig. 3, 3 _a_). Sh.e.l.l elongate, turreted, rather solid, covered with an (olive?) epidermis, and marked with fine longitudinal oblique red lines which extend from suture to suture. Whorls probably about 10, flat or even a little concave at the sides, shouldered above, usually with a spiral shallow groove and a few striae near the shoulder, and marked with fine incremental striae. Suture deep, slightly oblique. Last whorl long, finely transversely striated, most distinctly at the base. Aperture elongate-pyriform, acute above, effuse at the base.

Outer lip thin, sharp, accurate, and prominent at the middle.

Columellar margin rather thickly covered with callus, united above to the outer lip. Length of two specimens, consisting of five whorls 30 and 25 millim.; diameter 11 and 10; aperture 14 and 12 long, 6 and 5 wide.

(45) _Melania ugiensis._ (Plate x.x.xVII. fig. 4.) Sh.e.l.l subulate, ac.u.minate, beneath the epidermis (which is wanting in the specimens at hand), of a dirty, pale, livid, or purplish tint. Whorls probably about 14 in number; the eleven remaining are a little convex, rather slowly enlarging, and sculptured with close-set, obliquish, fine riblets, which are crossed by crowded spiral striae. Last whorl large, with the riblets rather obsolete below the middle, and very close together, much more numerous than those upon the upper whorls.

Aperture obliquely pear-shaped. Length 25 millim., diameter 8; aperture 8 long, 4 wide.

(46) _Melania sanctae annae._ (Plate x.x.xVII. figs. 5, 5 _a_.) Sh.e.l.l small, ac.u.minately pyramidal, somewhat eroded towards the apex, covered with a yellowish-olive epidermis, and sometimes marked with a few indistinct, reddish, irregular spots, and lines near the middle of the body-whorl. Whorls 5-6 remaining, flattish at the sides, divided by a slightly, oblique, distinct suture, all with the exception of the last one or two more or less distinctly, longitudinally, finely plicate; the plicae are more conspicuous in some specimens than in others, being at times entirely eroded. The other sculpture consists of fine lines of growth, and a few rather distant spiral striae, which cut across the incremental lines and produce a puckered appearance. Aperture elongate, pyriform, pale bluish within. Length of specimen consisting of six whorls 13 millim., diameter 5; aperture 5 long and 2 wide.

(47) _Melania guppyi._ (Plate x.x.xVII. figs. 6, 6 _a_.) Sh.e.l.l slenderly ac.u.minate, covered with an olive-brown epidermis. Whorls about 14, divided by a very oblique, deepish suture, concave above the middle and somewhat convex below it, and then contracted; ornamented with a few spiral series of nodules (about five on the upper whorls) and rather indistinct, very oblique and flexuous, longitudinal ridges, upon which the nodules rests, also exhibiting very sloping and flexuous lines of growth; the most conspicuous rows of granules are near the middle of the whorls. Aperture pyriform.

Outer lip thin, remarkably sinuated above towards the suture, and arcuately prominent below. Columellar margin oblique, straightish, covered with a callus, curving into the broad basal sinus. Length 31 millim., diameter 7; aperture 9 long, 4 wide.

This is a very remarkable and distinct species, with a very drawn-out spire, peculiar granuled sculpture, and a deeply sinuated labrum. I have much pleasure in naming it after Mr. Guppy.

(66) _Unio guppyi._ (Plate x.x.xVII. figs. 8-8 _b_.) Sh.e.l.l elongate, very inequilateral, usually a little longer than twice the height, compressed, covered with a blackish-brown epidermis, exhibiting strong lines of growth, and very faint radiating substriation, and marked with fine wrinklings at the eroded beaks, which are small and placed quite near the anterior extremity. Dorsal margin behind the umbones almost straight or the least excurved for some distance, then at an obtuse angle becoming oblique before rounding into the extremity, which is a little more sharply curved than the anterior end. Ventral outline either faintly excurved, straight, or the least concave. Interior bluish-white, most iridescent at the hinder extremity, generally stained in parts with olive-brown. Cardinal tooth of the right valve moderately large, four or five-lobed at the top, situated just in front of umbo. Between it and the outer margin is a short ridge, the s.p.a.ce between the tooth and the ridge receiving the single, smaller, roughened, and striated tooth of the left valve. Lateral tooth of the right valve long, obliquely truncate behind, fitting in between two teeth in the opposite valve.

Anterior adductor scar deep, posterior superficial, squarish in front. Pedal scar in both valves under the cardinal tooth very deep.

Ligament elongate, prominent.

Length 80 mm.; height 38; diameter 21.

70 mm.; 35; 18.

This species recalls to mind some of the forms from Australia and New Zealand. Its princ.i.p.al features are the elongate compressed form, dark brown colour, wrinkled apices, and coa.r.s.e incremental lines. It is the only species as yet recorded from the Solomon Islands.

ADDITIONAL NOTE. (H. B. GUPPY.)

A species of the _Litoritinidae (Littorina scabra)_ is commonly found in this group on the leaves and trunks of mangroves, Barringtonias, and other littoral trees, the branches of which overspread the rising tide.

These molluscs occur at heights varying from one or two feet to eight or nine feet above the high-water level; and they possess an unusually delicate operculum as compared with those of other species of the same family. They do not seem to be able to withstand immersion in salt water for any length of time, since out of six individuals kept submerged for twenty-four hours, three died. When first placed in the water, they were evidently very much out of their element, and tried in vain to creep out of the vessel. The delicate character of the operculum indicates a transitional stage between marine and terrestrial molluscs; and the experiment above referred to, throws a little light on this subject, since only the younger of the six individuals survived. One would have expected that the younger individuals would have been less able to withstand immersion in sea-water, but such was not the case, since they recovered from an immersion which killed the older individuals. In explanation of this unexpected result, I would infer that, on the theory of the inheritance of peculiarities at corresponding ages, the younger individuals would retain more of the marine habits of the original parent of the species, because in the first place only the adults of this parent species would have been modified to suit the new condition.

CHAPTER XVII.