PLATE LXXXII—Continued. 
Figs. 14-]6 Dorsal, profile and ventral views ; showing the plication, contour and i^ustulose exterior. X 3. 
Fig. 17. The interior of a brachial valve ; showing the cardinal ai’ea, wide delthyrium and well developed 
teeth. X 2. 
Fig. 18. A view looking into the umbonal cavity of the pedicle-valve to show the elevation of the teeth 
X 3, 
Fig. 19. Cardinal view of the specimen represented in tigs. 14-16 ; showing the cardinal area on each 
valve, the open delthyrium and cardinal process. X 3. 
Fig. 20. The interior of a brachial valve. X 2. 
Fig. 21. An internal cast of the pedicle-valve : showing the muscular imxiressions. X 2. 
Figs. 22, 23. Interiors of brachial vab’es ; showing cai-dinal jirocess and muscular impressions. X 2. 
Fig. 24. Interior of a brachial valve ; showing the cardinal area and process, crural plates and musculai- 
scars. X 3. 
Fig. 25. An enlai’gement of the external suid'ace ; showing the radiating rows of elongate pustules. 
Hamilton shales. From various localities in Western New Ym-k. 
Genus TEOPIDOLEPTUS, HalL. 
Page 302. 
Tkopidolepti.^8 carinatus, Conrad. 
Fig. 26. The pedicle-valve of a very young shell; showing the acuminate cardinal extremities and the 
coarse, simple and sharp plication. X 3. 
Hamilton group. Canandaigua Lake, New York. 
Fig. 27. An enlargement of an interior layer of the shell; showing puncta;. 
Fig. 28. A horizontal section of tlie shell sulistance ; showing the radial I'ows of oblique tubules penetrat¬ 
ing the fibrous shell substance. 
Fig. 29. Cai-dinal view of the umbonal portion of the valves : showing the open delthyrium, the great de¬ 
velopment of the chilidiuni, and the cardinal area X 3. 
Figs. 30-32. Ventral, profile and dorsal views of an average example; showing the characters of the ex¬ 
terior. 
Fig. 33 An internal cast of a large pedicle-^■alve ; showing the impression of the area, pedicle-cavity, teeth 
and dental I’idges. 
Fig. 34. An internal cast of a brachial valve ; showing the impression of the cardinal process and crenn- 
lated dental sockets. 
Fig. 35. The interior of a pedicle-^'alve ; showing the cai'dinal area, open delthyrium and the prominent 
crenulated teeth. 
Fig. 36. The interior of a brachial valve ; showing the cardinal process, crenulated dental sockets and 
median septum. 
Hamilton gi-OLuj. From various localities in the argillaceous and arenaceous shales of 
Central and Western New York. 
TrOPIDOLEPTUS . OCCIDENS, Htlll. 
Fig.s. 37, 38. Dorsal and ventral views of the (U'iginal specimen of the sjiecies. 
Hamilton group. Lma City, Iowa. 
