PLEIOCENE FOSSILS. 43 



ABCA SCALARIS.— Con. 



Plate XVI., Figs. 1 and 2. 



Area Scalaris, Con., Proc. Ac. Nat. Sci., Vol. L, p. 324. 

 Area Scalaris, Con., Foss. Ter. For., p. 59, pi. 31, fiig. 1. 



A. testa ovata, obliqua, radiatim costata ; costis quatuor et vigintij latere buccali brevi ; 

 latere anali oblique producto ; costis, valval dextralis, nodoso-crenatis, valvce sinistralis oblique 

 crenatis / area ligamenti brevi, sublata. 



Description. Shell ovate oblique, radiately ribbed, ribs twenty-four ; buccal side short ; 

 anal side obliquely produced ; ribs of the right valve nodulously crenulated, of the left 

 valve obliquely crenulated ; ligament area short, somewhat wide. 



This fossil seems closely allied to the preceding species. The points of difference are, 

 however, very considerable. Besides attaining a greater size, A. scalaris is more oblique, 

 has the ribs on the right valve larger and more strongly crenulated ; whilst on the left valve, 

 the ribs are coarsely crenulated on the buccal margin, flattened in the middle of the valve, 

 and covered with oblique crenulations. Both valves are carinated towards the anal margin. 



Plate XVI. , Fig. 1. Exterior of left valve, hinge and teeth of right valve. 



" 2. End view of fossil, showing outline, hinge and umbones. 



Locality. Darlington District. 



Museum, College of Charleston. 

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