FIGURK 10. Cardinal view of an adult specimen ; showing the asym- 

 metrical shell. 



FIGURE 10a. Dorsal view of the same. 



FIGURE 106. Ventral view of the same, (llth Ann. Kept. State 

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



DICTYONELLA RETICULATA HALL (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 the internal plate. X 2. 



(Figures 13, 13a, from the 28th Kept. N. Y. State Mus. Nat. Hist., pi. 

 26, figs. 53, 54.) 



ANASTROPHIA INTERNASCENS HALL (PAGES 337-339) 



FIGURE 14. Ventral view of the youngest specimen observed ; length 

 2 mm. 



FIGURE 14. 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 16a. Profile of the same ; showing the relative convexity of 

 the valves. 



(Figures 15-16a from the 28th Kept. N. Y. State Mus. Nat. Hist., pi. 26, 

 figs. 49, 45, 44.) 



CAMAROTCECHIA INDIANENSLS HALL (PAGES 346-351) 



FIGURE 17. The earliest stage of growth observed, the shell having 

 a length of .65 mm. The characters are essentially primitive ; the sur- 

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

 even marginal thickening. 



FIGURE 17a. 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. 



