334 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION". 



disconnected, like those of a cork-screw. Each turn 

 measures about 0-58 inch across, and there are five turns 

 in a length of 2*15 inches. It is smooth, and shows no 

 organic structure under a common pocket lens, the organic 

 matter having been replaced by the fine sediment of 

 which the matrix is composed. Unless these are the 

 tendrils or root-like appendages by which some floating 

 plant clung to marine bodies, I can form no conjecture in 

 regard to their nature. (See p. 333.)] 



Anomia Flemingi. (N. S.) 



Two different specimens of this species. The fine concentric lines representing 



shading. 



[Shell oval or sub-circular, compressed plano-convex, 

 extremely thin and fragile. Lower valve flat and ap- 

 parently more nearly circular than the other. Upper 

 valve depressed, convex, rounded in front, and more 

 broadly and less regularly rounded on the ventral side ; 

 posterior margin obliquely sub truncate from the dorsal 

 side, rather abruptly rounded, and waved so as to form a 

 broad very obscure fold at its connexion with the ventral 

 margin ; beak small, compressed, located near the middle 

 of the cardinal edge, but not projecting beyond it. Sur- 

 face marked by small obscure lines of growth. Length 

 1*10 inches ; breadth from beak to opposite side, 1 

 inch. 



