I’l.ATK L—(yOiitinueii. 
Subgenus HOMa^OSPIEA, s.-gen. nov. 
rage 11>. 
lioMOiosBiitA SOBKINA, Beechcr and Clarke. 
Fig-. 26. A ventral view of an individual of about average size. 
Figs. 27, 28. Profile and dorsal views; showing the convexity of the valves and the character of the plica¬ 
tion and concentric ornamentation. X 2. 
Niagara gi-oup. Waldron, Indiana. 
Genus RHYNCHOSPIRA, Hall. 
Page 108. 
Rhynchospira Electra, Billings. 
Figs. 29-31. Dorsal, ventral and profile views of the oi-iginal specimen. 
Lower Helderbei-g group. /Square Lake, Maine. 
Subgenus H0M(H0SPIRA, s. gen. nov. 
Pago lit, 
Homceospira (cf.) EVAX, Hall. 
Fig. 32. A dorsal view of an average specimen; showing the character of the deltidial plates and the sur¬ 
face plications. X 2. 
Fig. 33. 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 cai-dinal portion of the last specimen, enlarged to show in more detail the structure of the 
hinge-plate. X 5. 
Upper Silurian. Peri'y county, Tennessee. 
Genus 'FRIGERIA, Baylb. 
Page 265. 
Trigeria lepida, Hall. 
Figs. 36-38. Dorsal, ventral and profile views of a typical specimen ; showing the character of the exterior 
and the foi-m of the deltidial plates. X 2. 
Fig. 39. A dorsal view of a more 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 form of the foramen and its encroachment upon the apex of the valve. X 6. 
Hamilton group. Canandaigua Lake, N. Y. 
(The lithogi-ajihing of this plate was comj)leted before the discovery of the fact that this species 
is a terebratuloiil allied to Rensselairia, and referable to the genus Trigeria, Bayle, as inter- 
X^reted in this woi-k.) 
Genus RHYNCHOSPIRA, Hall. 
Pago 108. 
Rhynchospira (?) Eugenia, Billings. 
Figs. 41-43. Dorsal, ventral and xn'otile views of a sxieciinen; showing the usual form of exterior at this locality. 
X 2. Hamilton grou]). York, N. Y. 
Rhynchospira (?), sp. 
Fig. 44. A view of the exterior of a xiedicle-valve, the only sxiecimen of the species observed, and referred 
to this genus with doubt. 
Waverly group. Non'tlmesterii 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 tyiiical i-exn-esentatives of the genus. 
Waverly groux). McKean county, Pennsylvania. 
Genus CAMAROSPIRA, gen. nov. 
Page 82 
Camarospira Eucharis, Hall. 
47. Dorsal and ventral views of the exterior. The xiosition of the median sexitum is seen through 
the shell-substance on each valve. 
A xo’otile view ; showing the convexity of the valves. 
Corniferous limestone. Cass county, Indiana. 
A dorsal view of the original examx>le of Camarophoria Eucharis; showing a rather more pro¬ 
nounced median fold on the brachial valve. 
A ventral view of a specimen broken so as to exxiose the sxiondylium of the pedicle-valve. 
Corniferous limestone. Cayuga, Ontario. 
A median longitudinal section; showing the sxiondylium and suxuiorting septum of the pedicle- 
valve and the septum of the brachial valve. X H- 
A transverse section in the umbonal region ; showing the sxiondylium and septa. X 1-|. 
Corniferous limestone. Cass county, Indiana. 
Figs. 46, 
Fig. 48. 
Fig. 49. 
Fig. 50. 
Fig. 51. 
Fig. 52. 
