FiciiTin 10. — CanliiKil \ iew of an adult spicnincii ; showing the as^m- 

 inetrical sliell. 



FniUUK lll'f. — Dorsal view of Ihe same. 



Fiiiruio 106. — W'ntral view of the same. (11//* Jun. Kept. Stale 

 Gcvl. Iml., pi. '-'T, tiys. 21, I'J, 20.) 



DICTVOXELL.V UETICL'LATA ILvll (Pages :i:J5-:i37) 



Fic.ruE 11. — .V younj;' individual having a luiic^th and width of 

 o mm.; sluiwing the sidj-circular outline and undefined median inld. 



FiiJi'ui.: 12. — /Vxial sertiou of a larger, but immature form; iudicat- 

 in;;' the oliaraet(.T ot the articulation, and showing the internal ventral 

 plate and dorsal septum. 



FutUKK V'l. — Dorsal view of an adult shell. X 2. 



FiGL'RE F! rt — C'arilinal view of tin.' same; sliowing ll](.' liare umbonal 

 art'a and the lines of lateral attarliiucnt of tlie internal plate. X 2. 



(Figures l:j, Fix, from the 2s//i i,',y;/. X Y. Stale Mus. Nut. Hist., pi. 

 20, tigs, ."):), .')!.) 



ANASTltOFIIIA IXTFKXASCEXS Hall (Faciks :);i7-:j:i;i) 



Figure 14. — \'entral view of the yoiin^i'st specimen observed ; length 

 2 mm. 



Figure 1 la. — Outline profile of the same; showing the elevation of 

 the ventral beak and cardinal area. 



Figure 15. — Dorsal view of a lai ne adult. 



FiGiiiE 10. — \'entral view of an average aiUilt ; showing the (ner- 

 lapping dorsal valve. 



Figure 1Gc(. — Profile of the same ; showing the relative e(jnvexily of 

 the valves. 



(Figures 15-1 On from the 28(A liepl. .V. )'. Stale Mus. Nat. IIlsl., pi. 26, 

 figs. 40, 15, II.) 



CA.MAROT(ECIIIA IXDIAXFXSIS Hall (Pages :U6-351) 



Fn;uRE 17. — The earliest stage of growth observed, the shell having 

 a length of .05 mm. The oharaeters are essentially primitive ; the sur- 

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

 even rnai'ginal thickening. 



FiGuitE 17f/. — Outline profile of the same ; showing the elevation of 

 the ventral umbo. 



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

 of 1.5 mm. AV^ith th(! formation of the first growth-line, a number ot 

 faint plications have appean.-d, and the margins of the foramen have 

 become thickened. 



Figure 18a. — Outline profile of the same. 



