JURASSIC FOSSILS. 43 



FAMILY LIMDXJ1. 



GENUS LIMA, Bruguiere, 1792. 

 LIMA ? SINUATA, Meek. 



PI. 7, Fig. 4, and 4 a. 



SHELL (left valve) broad, suborbicular; compressed and rounded 

 in outline behind; moderately convex anteriorly; basal margin 

 rounded; anterior side sinuous and distinctly gaping above, 

 prominent and narrowly rounded below. Surface ornamented 

 by from ten to twelve distinct radiating costae, one-half to one- 

 third as wide (at the border) as the depressions between. Costse 

 simple, extending to the beak, and more or less roughened or 

 subnodose from the crossing of the concentric wrinkles of growth. 

 (Ears and point of the beak unknown.) 



Diameter, from the hinge to the ventral margin, 3.10 inches ; 

 antero-posterior diameter, 3.35 inches ; convexity (left valve only), 

 about 0.60 inch, 



The foregoing description was drawn Up from a cast of a left valve, with some 

 remaining fragments of the shell attached, but not in a condition to show tho 

 finer surface-markings or ears. Indeed, until better specimens can be collected 

 for examination, its generic relations must remain doubtful. In the forward 

 curvature and attenuated character of the beak, it presents much the appearance 

 of the curious Jurassic genus Trichites. The absence, however, of any traces of 

 the prismatic shell-structure of that genus, if not due to metamorphic agencies, 

 would alone exclude it from that group. In addition to this, it presents unques 

 tionable evidences of having the anterior side distinctly gaping, as seen at g, in 

 the profile, figure 4 a, plate 7 ; while in Trichites the valves are said to be closed 

 all around. I suspect it will be found to present characters that will require for 

 its reception the establishment of a new genus. 



