PLATE HE. 



LiNDSTRCEMELLA ASPIDIUM, Hall. 



Page 334. 

 Figs. 1, 2. Interior and internal casts of a brachial valve to which a portion of 

 the shell adheres, showing the strong lateral ridges, faint median septum 

 and obscure muscular impressions . 



Fig. 2a. Outline profile of conjoined valves of a smaller example, the pedi- 

 cle-valve being at the left . 

 Hamilton group , Near Hamilton, N. Y. 



Fig. 3 . A natural cast of the exterior of a large pedicle- valve ; showing the 

 character of the surface ornament and the peculiar undulation of the con- 

 centric ridges on approaching the pedicle-area. The pedicle-passage 

 differs from that in the normal mature Orbiculoidea in not being closed , 

 though its margins appear to be in contact . 

 Hamilton group . Near Leonards vide, N. Y. 



Fig. 4. A small pedicle- valve, with characteristic ornamentation and strongly 

 developed forg,minal groove. 

 Hamilton group. Darien, N Y. 



SCHIZOCEATSIA SCHUCHEETI, Hall. 



Page 334. 

 Fig. 5. A small brachial valve retaining most of the external surface, x 3. 

 Fig. 6. A large brachial valve, showing the posterior muscular scars, x 3. 

 Fig. 7. An individual from which most of the upper valve has been removed 

 exposing the flat pedicle-valve, x 3. 

 Hudson River group. Covington, Kentucky. 



ScHizocEANiA (?) Heldeebergia, Hall. 



Page 334. 

 Fig. 8. The lower exterior surface of an individual, showing the coarsely 

 radiate surface of the pedicle-valve, and the overlapping edges of the 

 finely striated pedicle- valve, x 2. 



Fig. 9. The internal surface of the pedicle-valve, showing a broad pedicle-fis- 

 sure and the overlapping margins of the upper valve, x 3. 

 Lower Helderberg group. Near Clarksville, N. Y. 



Cea^ia agaeicinAj Hall. 



Page 335. 



Fig. 10. An individual attached to a branch of Trematopora ; showing the 

 sparse and relatively coarse radiating ribs, x 3. 

 Lower Helderberg group. Near Clarksville, N. Y. 



378 



