3o6 NORTH AMERICAN INDEX FOSSILS. 



''^'^w^SsF^' 



Fig. 382. Tropidoleptus carinatus. External and internal views (Pal. N. Y., IV.). 



dinal area. Surface marked only with a few concentric growth 

 lines. 



Washitan of Texas, Vancouver Island. 



XCVI. Terebratella d'Orbigny. 

 Plicated Terebratuloids, with straight or slightly curved hinge 

 line. Loop composed of descending and ascending branches, sup- 

 ported by a median dorsal septum throughout life or only in the 

 younger stages. Lias-Recent. 



305. T. plicata (Say). (Fig. 383.) Cretacic. 



Subcircular, somewhat plano-convex, marked by 8-12 or some- 

 times more, sharply angular plications which extend from beak to 



FlG. 383. Terebratella plicata. Dorsal and side view ; and interior of brachial valve 

 enlarged. (After Whitfield. ) 



front. Pedicle valve strongly convex with an erect beak of small 

 size; foramen large. Structure strongly punctate. 



Upper Cretacic (Matavvan and Monmouth) of New Jersey, etc. 



