PLATE 3. 

 Photographs of Triarthrus becki, made by C. E. Beecher. 



Fig. i. Specimen 204. See also text fig. 42 and pi. 4, fig. 6. The exopodites and 

 endopodites of the first few segments of this specimen are better preserved than those of 

 any other revealing them from the dorsal side, x 9.5. 



Fig. 2. Specimen 220. A large individual exposed from the lower side. It shows 

 well the endopodites and part of the exopodites, and, rather better than any other specimen, 

 the endobases of the coxopodites. x 2.4. 



Fig. 3. Specimen 216. A small entire specimen showing considerable of the detail of 

 the appendages of the cephalon, and some of those of the remainder of the body, x 7.4. 



Fig. 4. Specimen 201. This figure shows the details of the appendages of the left 

 side and of the pygidium. Note the plate on the median line back of the pygidium, the 

 sockets for spines, and the terminal spines on the anterior endopodites. See also pi. 2, fig. 

 i and pi. 4, figs, i, 2. xf.i. 



Fig. 5. Specimen 207. One half of the posterior part of the thorax and pygidium, 

 showing exopodites and endopodites as seen from the dorsal side, x 7.6. 



Fig. 6. Specimen 214. The exopodites have been turned back nearly parallel to the 

 axis of the shell. Notice particularly the long flattened sete and the spinose spatula-shaped 

 terminal portion of each shaft. See also pi. i, fig. 2. x 7. 



