43 St. Maurice and Claiborne Pelecypoda 43 



of teeth small and nearly eqnal, the posterior one rather the smaller ; fosset 

 on the plate and immediately under the beak, oblique ; cavity of the shell 

 shallow; margin entire; nacre apparently not pearly. 



Diam. . . Length, i, Breadth 3-2oths of an inch. 



A single valve only of this truly interesting little Nucula has been ob- 

 tained by me. It differs in outline from any species I am acquainted with, 

 its trapezoidal form being very peculiar. At first sight, upon examination 

 of the teeth, I took it to be a Pectunctdus, but a further examination with 

 the microscope showed me the fosset for the ligament, between the two 

 series of teeth. It has a distinct fosset, but unlike the genus generally in 

 this, it is placed above the teeth, and directly at the point of the beak. We 

 may with great propriety, consider this to be the connecting link with the 

 Pedunculi, the "nuance" being into that of the P. ellipsis (nob). A more 

 complete junction could scarcely be established. 



This is a well-defined but very rare .species. Neither Greg- 

 oriornor Cossman seemed to have obtained specimens of it. Ball's 

 remark that it should be referred to Trinacria seem to indicate 

 that he had specimens before him in 1895. 



The sinuo,sity of the posterior margin is generally well-de- 

 fined, likewise a basal emargination. Fig. 8, however, is quite 

 regtilar in outline. 



Type. — Probably one of the three specimens found glued on 

 the some card and labelled Nucula pcduncularis, catalogued by 

 the writer as 5404 of the Acad. Record. Lea sa^-s he had but 

 "a single valve." 



Locality and Jiorizon.—C\2X\iOX\\& "sand" at Claiborne, Ala. 



Trinacria ovalls, n. sp., Ph 19- Fig- 9 a. 



Specific characterization. — Form and size as figured ; sub- 

 stance of shell rather thin ; somewhat inflated centrally ; main 

 shell surface and post-umbonal slope not sharply differentiated ; 

 posterior margin rounded, non-truncate and not pointed basally ; 

 radiate ornamentation fine and weak. 



From the St. Maurice formation as the ba.se of the Claiborne 

 bluff, above the Upper Landing, just below the Ferry. 



Type. — Paleont. Mus., Cornell Univ. 



Trinacria perplana Conrad, PI. 19. Figs. 10,11. 



Pectunculus perplauHS Con., Jr. Phila. Acad. Nat. Sci., ist ser., vol. 7, 

 1834, p. 134. (Not in Foss. Sh. &c., p. 40. as stated by Conrad in 



