ri.ATE, L— Continued. 



Subgenus HOMCEOSPIRA, s.-oen. nov. 



I'age Hi. 



HoMCEosriKA SOBKINA, IJccchor and Clarke. 



Fig'. 36. A ventral view of an in<livi<liial uf aboul average size. 



Fi(f8. 27, 28. Piiifile and >)oi-8mI views; showing llio convexity of the valves and the character of the plica- 

 tion and concentric ornamentation. X 2. 



Niagara group. IValdron, Indiana. 



Genus RHYNCHOSPIRA, Hall. 



I'aite 108. 



RHYNCHOSPIRA Electra, Billiiigs. 



Figs. 29-31. DorsaJ, ventral and i>rotile views of the original specimen. 

 Lower Helderbei-g group. Square Lake, Maine. 



Subgenus IiOM(-EOSPIRA, s. gen. nov. 



Homceospira (cf.) EVAX, Hall. 

 Fig. 82. A dorsal view of an average specimen ; showing the chara4;ter of the deltidial plates and the sur- 

 face plications. X 2. 

 Fig. 3.S. The interior of a pedicle-valve. 



Fig. 34. The interior of a brachial valve; showing the hinge-plate and median septum. X 2. 

 Fig. 35. The cardinal portion of the last specimen, enlarged to show in more detail the structure of the 

 hinge-plate. X 5. 



Upper Silui-ian. Perry couTiiy, Tennessee. 



Genus TRIGERIA, Batle. 



Page 265. 



Trioeria lepida, Hall. 

 Figs. 36-38.- Dorsal, ventral and profile views of a typical specimen ; showing the character of the exterior 



and the form of the deltidial plates. X 2. 

 Fig. 39. A doi-sal view of a moi-e elongate shell, with a pronounced median sinus on the brachial valve. X 2. 

 Fig. 40. An enlargement of the umbonal region of the specimen represented in tig. 36 ; showing the delti- 

 dial plates, the foi-m of the foramen and its encTOachment upon the apex of the valve. X 6. 

 Hamilton group. Canandaigua Lake, N. Y. 

 (The lithographing of this plate was completed before the discovery of the fact that this species 

 is a terebratuloid allied to Rk.ns8kl.«kia, and referable to the genus Tbiqbbia, Bayle, as inter- 

 preted in this woik.) 



Genus RHYNCHOSPIRA, Hall. 



PaKC 108. 



Rhynchospira (?) P^ugenia, Billings. 

 Figs. 41-43. Dorsal, ventral and profile views of a specimen; showing the usual form of exterior at this locality. 

 X 2. Hamilton gi-oup. Yin-k, N. T. 



Rhynchospira (?), sp. 



Fig. 44. A view of the exterior of a i>edicle-valve, the only specimen of the species observed, and referred 

 to this genus with doubt. 



Waverly group. NorthtDestem Pennsylvania. 



Rhynchospira scansa, sp. nov. 



Fig. 45. A view of the exterior of a pedicle-valve ; showing a median sulcus similar to that occurring in 

 the typical i-epresentatives of the genus. 



Waverly group. McKean county, Pennsylvania. 



Genus CA.MAROSPIRA, gen. nov. 



Page Si 



Camarospira Eucharis, Hall. 



Figs. 48, 47. Dorsal and ventral views of the exterior. The position of the median septum is seen through 



the shell-substance on each valve. 

 Fig. 48. A profile view ; showing the convexity of the valves. 



Corniferous limestone. Cass county, Indiana. 

 Fig. 49. A dorsal view of the original example of CamaropJioria Eucharis ; showing a rather more pro- 

 nounced median fold on the brachial valve. 

 Fig. 50. A ventral view of a specimen broken so as to expose the spondylium of the pedicle-valve. 



Cornifei"oU8 limestone. Cayuga, Ontario. 

 Vig. 61. A median longitudinal section ; showing the sjiondylium and supporting septum ef the pedicle- 

 valve and the septum of the brachial valve. X H- 

 Hg. 52. A transvei'se section in the umbonal region ; showing the spondylium and septa. X H. 

 Corniferous limestone. Cass county, Indiana. 



