Fig. 16. 



PLATE XV'A— Coatinaed. 

 Fi" 15 The iiitei-ior of a brachial valve. The cardinal pi'ocess consists of two indejiendent apophyses, 

 " "' not coalesced with the cniral plates, the latter being depressed at their origin but considerably 

 elevated at thfii' extremities. The visceral region is concave on either side of a broad median 

 riiige and its surface radially sti'iated ; from its anterior margin the surface of the valve is 

 abruiitly and evenly deflected. X 5. 

 Cardinal view of the same specimen ; showing the wiilth of the area, the postenor face of the car- 

 dinal process and the elevation of the crural ])Iates. X ». 

 These figures are from the original specimens of the species. 



"Point Levis; in the upper part of the Limestone No. 2, Quebec group." (Billings.) 



Genus ANOPLIA, gen. nov. 



(See Plate XX.) 

 Page 309. 



Anoplia nucleata, Hall. 



Fig. 17. Cardinal view of an internal cast of the pedicle-valve, retaining the impiessions of the extremely 

 olili(|ue dental lamelte and the short median septum ; also showing the indistinct outline of the 

 muscular area. X 3. 

 Fig. IS. The interior of the brachial valve which has a close similarity to that of Chonetes. X 2. 

 Oriskany sandstone. Albany comity, N. T. 

 See al.so the illusti-ations in Palseontology of New York, Volume III, plate 91, figs. 1 a-d. 



Genus LEPT.^NISCA, Beecher. 



Page 300. 

 LEPT.ffiNISCA CONCAVA, HuU. 



(See Plate XV, figs. 30, 31.) 

 Fig. 19. The exterior of a pedicle-valve ; showing the contour and character of the surface. X 2. 

 Fig. 20. The interior of a brachial valve, somewhat imperfect about the margins and cardinal jn-ocess, 



but showing the spii-al lirachial ridges and the thin median septum. X 2. 

 Fig. 21. Cardinal view of an imperfect bi-achial valve presei-ving the character of the cardinal process, 

 which is deeply quadrilobate. X 3. 

 Figures 20 and 21 are from specimens illustrated by Mr. Bekcher. 

 Lower Helderberg group. Near Clarksville, N. Y. 



Leptjenisca adnascens, sp. nov. 



Fig. 22. A j)edicle-valve attached by nearly its entire outer surface to the interior of a valve of Orthis 

 oblata. The specimen shows the dental lamella; and median ridge dividing the muscular ai-ea. 

 X 3. 



Fig. 23. A specimen retaining both valves, attached to Orthis perelegans. X 4. 

 Lower Helderberg group. Near Clarksville, N. T. 



Leptjsnisca tangens, sp. nov. 



Fig. 24. The exterior of a pedicle-valve with the umbo flattened from attachment, and showing the low 



median .sinus. X 2. 

 Fig. 25. The interior of the same specimen ; showing the cicatrix of attachment (x), the deltidiuni and the 



dental lamella' X 2. 

 Fig. 2ti. The exteiioi- of a pedicle-valve in which the rugose growth has obscured the median sinus. The 



deep umbonal depression has been caused by attachment to some bryozoan. X 3. 

 Figs. 27, 28. Opposite sides of a pedicle-valve attached to a twig of Trematopora. X 3. 

 Figs. 29, 30. Opposite sides of a similar valve which has been attached to a fi'ond of Fenbstella. X 3. 



The.se la-st two specimens show the bilobate exterioi-, the deltidium, teeth, strong dental lamellae 



liroduced about the muscular area, and the short median septum. 

 Lower Helihu-berg group. Near ClarkstHlle, N. Y. 



