FiGURK 10. — Cai'dinal view of an adult specimen ; sliowing the asym- 

 metrical shell. 



FiGURK lOrt. — Dorsal view of the same. 



Figure 106. — Ventral view of the same. (Wlh Ann. Rept. State 

 Geol. Ind., pi. 27, figs. 21, 19, 20.) 



DICTYONELLA RETICULATA Mall (Pages 335-337) 



Figure 11. — A young' individual having a length and width of 

 3 mm.; showing the sub-circular outline and undefined median fold. 



Figure 12, — Axial section of a larger, but immature form; indicat- 

 ing the character of the articulation, and showing the internal ventral 

 plate and dorsal septum. 



Figure 13. — Dorsal view of an adult shell. X 2. 



Figure 13 a — Cardinal view of the same; showing the bare umbonal 

 area and the lines of lateral attachment of tlie internal plate. X 2. 



(Figures 13, 13rt, from the 26th Kept. N. Y. State Mux. Nat. Hist., pi. 

 26, figs. 53, 54.) 



ANASTROPHIA INTERNASCENS Hall (Pages 337-33!)) 



Figure 14. — Ventral view of the youngest specimen observed ; length 

 2 mm. 



Figure 14o. — Outline profile of the same; showing the elevation of 

 the ventral beak and cardinal area. 



Figure 15. — Dorsal view of a large adult. 



Figure 16. — -Ventral view of an average adult; showing the over- 

 lapping dorsal valve. 



Figure 16«. — Profile of the same ; showing the relative convexity of 

 the valves. 



(Figures 1.5-lGrt from the 28/Z( Rept. N. Y. State Mu^. Nat. Hist., pi. 26, 

 figs. 4!), 4.3, 44.) 



CAMAROTCECIIIA INDIAXENSIS Hall (Pages 316-351) 



Figure 17. — The earliest stage of growth oliserved, the shell having 

 a length of .Go mm. The characters are es.sentially primitive ; the sur- 

 face is without plications, the foramen triangular and devoid of plates or 

 even marginal thickening. 



Figure 17«. — Outline profile of the same ; showing the elevation of 

 the ventral umbo. 



Figure 18. — A later stage of growth in which the shell has a length 

 of 1.5 mm. With the formation of the first growth-line, a number of 

 faint plications have appeared, and the margins of the foramen have 

 become thickened. 



Figure 18a. — Outline profile of the same. 



