PLATli XXIV—Continued. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
P'PERINEA (VeRXUMNIa) REVERSA. 
Page 104 
' See Plate 84. 
6. A large right valve. Another figure of this specimen is given on plate 84, fig. 24, to show the 
obsolescence of the rays on the wing. 
Chemung group. Elmira, N. Y. 
12. A specimen with the valves united along the hinge, showing the convex right valve and. flat or 
concave left valve. 
Chemung group. Chemung river, Upper Narrows, N. Y. 
Ayiculopecten princeps. 
See Plates 1, 5, 6 and 81. 
7. An enlargement, to two diameters, of the impression of the hinge, showing the striations of the 
” ligamental area. 
Hamilton group. Cazenovia, N. Y. 
Lyriopecten CYMBALON. 
Page 47. 
8. A large, perfect left valve. The specimen shows a striated ligamental area. • 
Hamilton group. From a boulder hear Elmira , N. Y. 
Pxerinea (Vertumnia) avis. 
Pkge'ioS . 11 !; - 
9. An imperfect right valve. 
Chemung group. NeaY. Elmira, N. Y. 
11. A large, convex right valve. The figure should be restored at the cardinal angles to correspond 
with fig. 13. 
Chemung group. Mansfield, Pa. 
13. A nearly entire left valve. The byssal sinus should be a little deeper than is represented. 
Chemung group. Near Elmira, N. Y. 
Pterinopecten suborbicularis. 
Page SO. 
See Plates 8 aiid 82. 
10. A view of a large and very perfect left valve. The radii increase by interstitial addition and not 
by bifurcation as is represented in the figure. 
Chemung group. Elm Valley, Alleghany Co., N. Y. 
Limoptera macroptera. 
Page 246. 
See Plates 26, 27, 28, 29 and 92. 
14. A small right valve showing the form and surface ornamentation. 
Hamilton group. Pratt’s Falls, Onondaga Co., N. Y. 
Allocardium alternatum, gen. et sp. nov. 
15. A view of the specimen enlarged to two diameters. The relations of this shell are not apparent. 
It has the aspect of a bivalve shell in the characters of the rays and the cardinal auriculation, 
and somewhat resembles Hippagus and Trigoniluna. With the present material it cannot 
be satisfactorily arranged wit'll any known genus of molluscs. 
Hamilton group. Cayuga lake, N. Y. 
