MIOCENE MOLLUSC A AND CEUSTACEA. 81 



Genus SYNDOSMYA Keclus. 



Syndosmya? nuculoides. 



Plate xv, figs. 7-9. 



Amphidesma nuculoides Conrad: Am. Jour. Sci., 1st. ser., vol. 41, p. 347; Miocene Foss., 



p. 73, PI. XI, fig. 0. 

 Abra nuculoides Con.: Acad. Nat, Sci. Phila., 1862, p. 574; Meek, Check List, p. 11. 



" Ovate, convex, very inequilateral, with very regular minute concen- 

 tric lines, posterior side subcuneiform ; extremity acutely rounded; lateral 

 teeth obsolete." (Conrad.) 



The specimen which I have referred to this species is about one-half 

 larger than Mr. Conrad's figure, but in other respects closely resembles it in 

 outline and general features. The shell is rather elongate-ovate, and mod- 

 erately convex, and extremely thin and delicate in texture. The beak is 

 small, situated rather within the anterior third • of the length, behind 

 which the shell is narrowed, the posterior end being more narrowly rounded 

 than the anterior; basal and cardinal margins subparallel ; surface with very 

 fine concentric lines only, and with a very faintly defined, oblique, mesial 

 sulcus. Internally there is a single, moderately strong, direct tooth beneath 

 the beak, with a deep, wide pit in front, in the right valve, and a slight pro- 

 jecting lamelliar tooth near its extremity. No appearance of a posterior 

 lateral tooth can be seen. Muscular imprints very faint, and pallial sinus 

 shallow and obscure. It is not an Abra, as there are no lateral teeth. 



Locality: Shiloh, N.J. From the collection of the National Museum; 



but only a single right valve observed. 

 mon xxiv 



