PLATE LXXX. 



(Fifmres 1-17, 2S-35 by R. P. Whitfield; 18-22, 36-39 by E. Emmons.) 



Genus CRYPTONELLA, Hall. 



Pago 286. 



Ckyptonella rectirostka, Hall. 



Figs. 1-3. Dorsal, ventral and jirofile views of a small shell with characteristic outline. 

 Fig. 4. Dorsal view of a large, somewhat distorted specimen, retaining the deltidial plates. 

 Hamilton shales. Caimndaigva Lake, Netc York. 



Ckyptonella planirostra, Hall. 



Fig. 5. Dorsal view of an average specimen retaining the deltidial plates. 

 Figs. 6, 7. Dorsal and protile views of a large and much thickened shell. 



Hamilton shales. Western New York. 

 Figs. 8, 9. Ventral and dorsal views of an intei-nal cast ; showing the muscular impressions and vascular 

 sinuses. 



Hamilton group. Hardy county, Virginia. 

 Fig. 10. An enlargement of the cardinal portion of the pedicle-valve ; showing the foramen, deltidial plates 

 and teeth. 



Hamilton group. Moscow, New York. 



Ckyptonella eximia, Hall. 



Fig. 11. Profile view of a somewhat gibbous shell ; showing the contour of the valves. 

 Fig. 12. An enlargement of the umbonal portion of the valves ; showing the foramen, deltidial plates and 

 cardinal slopes. X 3. 



Lower Helderberg group. The Helderbergs, New York. 



Subgenus CRAN.^NA, s.-oen. nov. 



Page 297. 



Cran^na Rominoeri, Hall. 



Figs. 13-15. Dorsal, ventral and profile views of a typical example ; showing the median sinus on the 



pedicle valve and the anterior emargination. X 2. 

 Figs. 16, 17. The loop of this species, greatly enlarged ; showing the divergence of the descending branches, 

 their short recurvature, and the conspicuous crural apophyses. 

 Hamilton group. ThuTider Bay, Michigan. 

 Figs. 18, 19. Dorsal and ventral views of a somewhat broader foim. 

 Hamilton group. lovoa Oily, Iowa. 



Genus.DIELASMA, King. 



Page 29,!. 



DiBLASMA Calvini, Hall and VVhittield. 



Figs. 20-22. Dorsal, profile and ventral views of a mature individual ; showing the form and contour of the 

 valves and retaining the foramen and deltidial plates. 

 Hamilton group. New Buffalo, Iowa. 



Subgenus EUNELLA, s..gen. nov. 



Page 290. 

 EUNELLA SULLIVANTI, Hall. 

 Fig. 23. An enlarged view, showing the loop. X 3. 



Comiferous limestone. Cayuga, Ontario. 

 Figs. 24-26. Dorsal, ventral and profile views of one of the original specimens. 

 Comiferous limestone. Columbus, Ohio. 



