The Appendages, Anatomy, and Relationships of Trilobites Part 35

PLATE 7.

Photographs of _Cryptolithus tessellatus_ Green, made by C. E.

Beecher.

Fig. 1. Specimen 233. The best preserved individual, the one from which Professor Beecher's drawing (text fig. 45) was made, and which served as the princ.i.p.al basis for the restoration (text fig. 20). Note the long, backward directed antennules, the abrupt backward turn of the outer portions of the endopodites, the way in which the exopodites extend beyond the endopodites, and the fact that alt are beneath the cover of the dorsal s.h.i.+eld. The hypostoma is turned entirely around.

10.9.

Fig. 2. Specimen 235. Half of the thorax and pygidium, with the appendages revealed from the ventral side. Note the abrupt manner in which the outer portions of the endopodites are turned backward. See also pl. 8, fig. 3, and pl. 9, fig. 1 (right half). 14.45.

Fig. 3. Specimen 236. Detail from fig. 4, to show the blade-like setae of the exopodites and the numerous terminal spines of the endopodites.

30.

Fig. 4. Specimen 236. The appendages of the thorax and pygidium, seen from the lower side. Specimen 236 is the right half of the same individual from which specimen 235 was obtained. Note the interarticular membranes between the segments of the endopodites and the blade-like setae of the exopodites. See also pl. 9, fig. 1 (left side). 19.

Fig. 5. Specimen 236. The same specimen, seen from the dorsal side, showing, when the test is removed, the long blade-like setae of the exopodites. See also pl. 9, fig. 2 (right half). 19.

PLATE VII.

HELIOTYPE CO. BOSTON

PLATE 8.

Photographs of _Cryptolithus tessellatus_ Green, made by C. E.

Beecher.

Fig. 1. Specimen 231. A nearly complete individual, cleaned from the ventral side and showing obscurely the hypostoma and fragments of numerous appendages. Note the lines of appendifers along the sides of the axial lobe. 11.

Fig. 2. Specimen 232. Although this is not very well preserved, it shows more of the cephalic appendages than any other. Even so, only just enough is shown to indicate that they were similar to those on the thorax. 12.

Fig. 3. Specimen 235. Dorsal side of the appendages of the thorax and pygidium. See pl. 7, fig. 2 for the ventral view. On pl. 9, fig. 2 (left side) is a drawing taken from the same specimen. 11.

Fig. 4. Specimen 238. Part of a thorax and pygidium, seen from the ventral side. The series of heavy segments shown in the upper part do not belong to one appendage, but are the distal ends of several endopodites. See also text fig. 46 for a drawing of this specimen.

18.

Fig. 5. Specimen 237. Pygidium and part of the thorax, with some of the appendages. 11.

PLATE VIII.

HELIOTYPE CO. BOSTON

PLATE 9.

_Cryptolithus tessellatus_ Green. Upper drawing by C. E. Beecher; lower drawing by Miss F. E. Isham, under the direction of C. E.

Beecher.

Fig. 1. Appendages of the thorax and pygidium, seen from the ventral side. These are not restorations, but drawings from the halved individual numbered 236 (right side of drawing) and 235. For photographs of these specimens, see pl. 7, figs. 2, 4. 20.

Fig. 2. Appendages of the thorax and pygidium, seen from the dorsal side. Same specimen as in fig. 1. For photographs, see pl. 7, fig. 5, and pl. 8, fig. 3. 20.

PLATE IX.

HELIOTYPE CO. BOSTON

PLATE 10.

From photographs made by C. E. Beecher.

Fig. 1. _Isotelus latus_ Raymond. Ventral surface of the specimen in the Victoria Memorial Museum at Ottawa, Canada. Note the large, club-shaped c.o.xopodites and the more slender endopodites. The first large c.o.xopodite back of the hypostoma belongs to the last pair of cephalic appendages. The c.o.xopodite of the appendage in front of it is seen turning in beneath the tip of the hypostoma. 2.

Fig. 2. _Isotelus maximus_ Locke. The ventral side of the specimen described by Mickleborough and now in the U. S. National Museum. The tips of the hypostoma may be seen at the front, and the first two pairs of c.o.xopodites behind them belong to the last two pairs of appendages of the cephalon. Note how much stronger the c.o.xopodites are than the endopodites. The appendages of the pygidium show but poorly, 1.45.

PLATE X.

HELIOTYPE CO. BOSTON

PLATE 11.

_Ceraurus pleurexanthemus_ Green. A restoration of the ventral surface and appendages, made by Doctor Elvira Wood, under the supervision of the writer, from data obtained from the translucent slices prepared and described by Doctor Walcott. 5.

PLATE XI.

HELIOTYPE CO. BOSTON