EXPLANATIONS OF PLATE III. 



PAGE 



Fig. 1. a, h, 0, (7, (', /. . GiiYPiivEA calceola, vo.r. nebuascensis 74 



. 1 a. Side view of a young or dwarfed specimen (under valvn), showing the incurred beak. 

 1 h. Side view of anotlier individual of the same size, witli the beak truncated. 

 1 c. Under view of tlie same, showing tlie longitudinal stria;. 



1 (/. Longitudinal striifi enlarged. 



■ \ e. A larger specimen, with the whole under side of the lower valve occupied by the scar of adhesion. 



■ 1/. Upper side of an upper valve. 



■ Fig. 2. a, b Pentacrinites asteriscus. . . .67 



2 a. One of the segments of the column, natural size. 



2 ft. The same enlarged. 



• Fig. 3. & 3 6. . • • LiNGUbA BREVIROSTRIS. . . . . CO 



3. The usual subovate form of the species. 



3 a. A narrower variety. 



Fig. 4 Rhynchonella ■ ? Dorsal valve 71 



Fig. b. a, b Volsella pertenuis. .80 



5 a. Side view. 

 5 6. Dorsal view. 



• Fi". (i CamPTONECTE-S ? PERTENOIfi. -.■^^'•'.■' . . . .78 



The figure represents a cast without the ears, and apparently with only concentric markings. 



Fi<r. 7 Tancredia Warrenana 90 



Fi"-. 8 Tancredia? .siquilateralis 00 



■ Fig. 9. a, b, c. . ■ Grammatodon inornatus 90 



9 a. Side view of a somewhat worn or macerated shell. 



9 6. An internal cast showing the impressions of the posterior hinge plates. Those of the anterior 

 side are not represented in the lithograph. 



9 c. An anterior view of one valve, showing its convexity, and the curve of the beak. 



Fig. 10. a, b, c, d, ti. . . Eu.microtis curta 81 



. 10 a. Side view of left valve. 



.10 ft. Radiating strife of same enlarged. 



10c. Right side of another specimen a little enlarged, showing the deep byssal notch or sinus; 

 also its concentric markings. The latter, however, are too distinct in the lithograph, and 

 curve in such a manner as to indicate that the outline of this valve was subseniicircular 

 when small, while it seems to have been of nearly the same form at all stages of growth. 



10 (^. Inner view of a left valve of another specimen ; the hinge margin, liowever, is broken away. 

 10 e. Anterior view of a specimen with the two valves united, though not quite closed below, and a 



little compressed above. 



• Kijr. 11. Tbioonia Conradi 83 



• Fig. 12. a, 6. . . . Astarte ? inornata. 94 



12 a. A left valve. 



12 6. Dorsal view of same. 



Fig. 13. a, b, c Unio nucalis 92 



13 a. Dorsal view. 



13 6. Side view, with anterior margin somewhat broken. 



■ 13 c. Hinge view of an imperfect specimen. The lithograph is not a successful representation of 



this hinge. It has a small compressed cardinal tooth under the beak, and a long sublaminar 

 posterior lateral tooth, with a furrow above it. for the reception of a similar tooth in the 

 other valve. 



