PLEIOCENE FOSSILS. 27 



PECTEN.— Gaultier. 

 PECTEN MORTON!— Rav. 



Plates LX. aitd X., Figs. 1 to 4. 



Pecten Mortoni, Rav., Proc. Acad. Nat. Sci., Vol. LT., p. 96. 



P. testa rotunda, compressa, tenui, cequivalvi, cequilaterali, utrinque Mante ; valvis, eztus 

 Icevibus, aut tenuissime concentrice striatis, intus costis radiatim angustis, bints. 



Description. Shell circular, compressed, thin, excepting at the base of the ears, equi- 

 valve, equilateral, gaping at both sides, concentrically marked with fine lines on the outer 

 surface ; interior suface with about thirty-seven narrow ribs, arranged in pairs, prominent 

 along the pallial edge, becoming obsolete with age, towards the hinge, and entirely wanting 

 in the buccal and anal margins. 



This fine fossil is not uncommon in South Carolina. It bears a striking resemblance to 

 P. pleuronectes and P. japonicus. From the former it is separated by greater size and 

 regularity of the ribs, and from the latter by their lesser number. P. japonicus having 

 from forty -four to forty-six, whilst P. mortoni rarely exceeds forty ; this, however, is a very 

 variable character, and the fossil stands very nearly related to P. japonicus. 



Plate LX., Fig. 1. Side view of shell, natural size. 



" 2. Lower valve. 



Plate X., Fig. 1. End view, to show the hinge. 



" 2. Interior of valve, to show ribs. 



Locality. Grove, Cooper River ; Smith's, Goose Creek. 



Museum, College of Charleston, S. C. 



