4S6 PALEONTOLOGY OF NEW-YORK. 



Eatoiiia peculiaris. 



Plate CL Fia. 2 a-g; and Platk CI A. Fia. 1 a - A. 

 For description of the species, see page 244 of tliis volume. 



PLATE CI. 



Fig. 2 a, b, c. i)or.sali ventral and profile views of a specimen, having the ordinary form 

 and proportions of this species in the Oriskany sandstone. 



Fig. 2 (/> A cast of the dorsal valve of this species, showing the median septum and lateral 

 lamellae. 



Fig. 2 e. A cast of the ventral valve, showing the form of the muscular impression, the 

 median septum, and the small points of attachment for the adductor muscles. 



Fig. 2yi A specitnen preserving a portion of the shell, which, on one side, is penetrated by 

 the ramifying vessels. ( The lamellose structure of the shell is confounded with 

 the surface striae in the figure, which gives it an unnatural appearance.) Figure 

 enlarged to one and a half diameters. 



Fig. 2 ^. A cast of the ventral valve, showing the musclilar and vasoular impressions ( See 

 corrected figure on Plate ci a). 



PLATE CI A. 



Fig. 1 a. Interior of the ventral valvCf showing the form of the muscular impressions, teeth, 

 etc. 



Fig. 1 b. Profile of the same, showing the little elevations of the shell-surface, and the small 

 pits for the adductor muscles a, and the teeth t. 



Fig. 1 c. The dorsal valve, showing the crural processes and muscular impression. 



Fig. 1 d. Front view of the same, showing the deep sinus, and the relation of the crural 

 processes and median septum. 



Fig. 1 «. Section of the dorsal valve, showing the elevation of the median septum and the 

 crural processes. 



Fig. 1 y. Figure of the ventral valve (the inflected extension in froat being removed ) with 

 a part of the dorsal valve attached, showing the crural processes c 1 and c 2, 

 and the median septum of the dorsal valve ; a, the adductor imprints, showing 

 the small oblique pits penetrating beneath the laminae of the shell ; r, the cardi- 

 nal muscular impression. 



Fig. 1 g. View of another specimen with the dorsal valve downwards and the ventral valve 

 broken away, to show the median septum articulating with the bifurcating cardi- 

 nal process of the dorsal valve. 



Fig. 1 A. A east of the ventral valve, showing the muscular and vascular impressions. This 

 and the preceding figure are enlarged to once and a half the natural size. 



Geological position and localities. In the Oriskany sandstone : Albany, Schoharie, 

 and Greene counties (New- York); Cumberland ( Maryland ), and other places. 



