PLATE XXX—Continued. 
Fig. 18. A larger example, retaining the “manubrium.” 
Hamilton group. Pratt’s Falls, Onondaga county. 
Fig. 19. A specimen in the shale, from which the ci'iist has been removed, showing the thickness of this 
crust over the ci’own and its comparative tenuity on the basal portion of the mandible. 
Hamilton group. Pratt’s Falls, Onondaga county. 
PALAiOPAL/EMON NeWBERRYI. 
Fig. 
Fig. 
Fig. 
Fig. 
Page 203. 
20. Lateral view of the type specimen, natural size. 
21. The same view, enlarged to two diametei-s. showing the somewhat ciaished and broken carapace, 
the bases of the strong antennse, the basal portion of an ocular peduncle, a joint of a maxillary 
palpus (?), and fragments of five pairs of ambulatory appendages. The abdomen is incurved, 
and is composed of five somites, the first two of which bear the bases of natatory appendages. 
The tail is expanded, and the posterior portion of it has been abraded. 
22. Dorsal view of the same specimen, natui’al size, showing the prominence of the antennse, the 
cai'inse on the carapace, and the incurvature of the abdomen. 
23. The tail, enlarged to two diameters, showing the broad, stout telson, the lateral spines with their 
short basal joints, and the flat, tenuous lamellar spines lying in the membranous expansion. 
Erie shales. (Portage group.) LeRoy, Lake comity, Ohio. 
TrOPIDOOARIS IIaMILTONI.E, 11. sp. 
Fig. 24. The type siiecimen, natural size. 
Fig. 25. The same, enlai-ged to two diameters. The specimen is folded along the hinge-line, the edge of 
the right valve being seen within the venti’al margin of the left. The outline of the cai'ajiace 
is closely similar to that of T. hicarinata of the Chemung group, being narrow near the ante¬ 
rior extremity, rajiidly widening posteriorly. Both dorsal and ventral margins are elevated 
and ornamented by transverse striations. A single nearly straight carina lies on the middle of 
each valve, and this is also sti-iated along its summit. An eye-node is visible near the anterioi- 
extremity of this carina. 
This specimen was obtained too late to permit a notice of the species in its pi’oper place in the text. 
Hamilton group. In the uppermost beds of the shales. Foste^'’s, Ca7iandaigua Lake. 
