48 PLEIOCENE FOSSILS. 



PECTUNCULUS LENT1FORMIS.— Con. 

 Plate XVII. Pig. 2. 



Pectunculus pidvinatus, Lam., Con., Foss. Shells, Ter. For., p. 17, tab. 2, fig. 2. 

 Pectunculus lentiformis, Con., Foss. Ter. For., p, 64, pi. 36, fig. 2. 



P. testa sub-orbiculari, crassa, sub-cequilaterali, costata, radiatim tenuiter striata; concen- 

 trice plicata; dentibus cardinalibus, crassis; area ligamenti striata. 



Description. Shell nearly orbicular, thick, almost equilateral; ribbed, racliately and 

 finely striate ; concentrically plaited ; cardinal teeth robust, oblique ; ligament area wide, 

 striate. 



The orbicular outline of this shell is greatly modified by age; the sides became thick- 

 ened and contracted, so that the buccal and anal margin appear to be slightly truncate. 

 The concentric increment lines become more numerous towards the pallial margin. The 

 teeth occupy about two-thirds of the hinge plate. The greater thickness of the shell and 

 the robust teeth, will serve to separate this fossil from its congeners. 



Plate XVII. Fig. 2, Exterior of left valve, and interior, hinge and teeth right valve. 



Locality. Darlington. 



Museum, College of Charleston. 



PECTUNCULUS PASSUS.— Con. 



Plate XVII. Pig. 3. 



Pectunculus passus, Con., Foss. Ter. For., p. 64, pi. 35, fig. 3. 



P. testa sub-orbiculata, sub-cequilaterali; latere buccali, costis evanescentibus, wmbonibus 

 inter sefere contingentibus. 



Description. Shell sub-orbicular, radiately striate; ribs disappearing in the buccal 

 margin; umbones nearly touching. 



