10 PALEONTOLOGY OF NEW JEKSEY. 



and are nearly all internal casts. In this condition they frequently afford 

 evidence of radiating strise, and correspond with the description given 

 above, but are different in form from those more advanced stages of 

 growth. As they advance in size the form changes from this nearly equi- 

 valve, lenticular form, by the front of the valves becoming elevated, 

 forming a fold on the dorsal side and a broad, shallow depression on the 

 ventral. This feature is increased with increased growth until they assume 

 the form given by Mr. Conrad for his Terebratida glossa. The form is then 

 elongate-ovate with very convex valves, the front of which is somewhat 

 produced into a pinched fold on the upper valve, and with a shallow depres- 

 sion on the opposite one corresponding to it. The beak of the ventral valve 

 becomes slightly incurved and is largely truncate, and its lateral margins 

 subangular. The ventral valve possesses a slight cardinal area on each side 

 of the foramen, which is flattened, and. the dorsal valve has lateral expan- 

 sions on the sides of the beak to correspond, and which form a slightly 

 extended cardinal line on each side of the beak. This is shown on the 

 medium-sized cast figured in the pouching of the lateral margins on the 

 sides of the beak of the dorsal valve, but it is not distinctly observable in 

 the larger figure, nor on the one copied from Mr. Conrad. On the former 

 specimen the striae are fine and even, but as it does not retain the shell they 

 are not seen on the upper part of the specimen. 



Dr. Morton first described this species from young specimens, and Mr. 

 Gabb seems to have considered it as identical with the young of T, Harlani 

 (see Synopsis, p. 194). This could not be the case with a shell possessing 

 the features described b)^ Dr Morton. Mr. Gabb also considered the small 

 shells as the same as T, lacliryma Morton ; being misled by specimens labeled 

 by Dr. Morton (see Synopsis, p. 200, foot-note), on ascertaining his mistake 

 he described the New Jersey shell as T. HaUiana. Mr. Conrad subsequently 

 obtaining adult specimens described and figured them under the name T. 

 glossa^ supposing it to come from the Eocene beds at Shark River, New Jer- 

 sey, which is a mistake. I believe them all to be only stages of growth of one 

 species; at least I have not seen specimens that I should consider as represent- 

 ing distinct species when the}^ are examined together and in numbers. There 

 are some of the small ones which are rather more ventricose than the ma- 



