18 PROCEEDINGS OF THE ACADEMY OF 



SANGUINOLARIA, Lamarck. 



Sanguinolaria ? leptogaster, n. sp. Shell small, thin, subquadrangular. 

 Beaks subcentral, flat, not elevated above the dorsal line. Posterior end ob- 

 liquely truncated ; anterior gently rounded below, abruptly above, with a 

 long deep lunette ; ventral side arcuate in the middle, joining the extremities 

 by a gradually increased curvature. Umbo flattened, a low ridge extending 

 obliquely to the posterior basal angle. Dorsal line straight behind the beaks, 

 joining the posterior side at an angle of 125. Surface marked by fine 

 regular striae parallel with the ventral and posterior margins. 



Length -53 (100) ; height -38 (71) ; thickness of valves -09 (17). 



BELLEROPHON, Montfort. 

 Bellerophon cyrtolites, Hall, (Thirteenth Rep. Reg. N. Y., p. 107). A 

 small Bellerophon, laterally appressed, and with an acute periphery, ap- 

 proaches too closely to B. cyrtolites to justify discrimination. It is known, 

 however, only by its cast, which is quite smooth. Should the identification 

 prove correct, this species occurs at Rockford, Ind., Marshall, Michigan, and 

 Burlington, Iowa. 



PORCELLIA, Leveille. 



Porcellia rectikoda, n. sp. Shell small, gradually enlarging, marked by 

 a series of transverse nodes, which are strongest on the dorso-lateral region, 

 and gradually diminish to the middle of the side ; transverse section between 

 two nodes subcircular. Dorsum unknown. 



Diameter of last whorl about "59 ; dorso-ventral diameter of tube near the 

 aperture *19. 



This species differs from P. crassinoda, White and Whitefield, in its circu- 

 lar section and transversely elongate nodes from P. obi i qui noda, White, in the 

 transverse position of the nodes and from P. nodosa, Hall, (Greol. Surv. la., 

 Supplem. to vol. i. part 2, p. 92), in its much smaller size and different 

 geological horizon, the latter being found in the upper bed of the Burlington 

 limestone, which has thus far furnished no species identifiable with fossils 

 from the sandstones below. 



DENTALIUM, Linnams. 



Dentalium GRANDiEVUM, n. sp. Shell rather large, perfectly straight and 

 terete, or a little compressed ; tapering *09 in one inch near the larger end, 

 less rapidly near the small end ; surface marked by faint, irregular incremen- 

 tal stri?e, which run obliquely around the shell, and in flattened specimens 

 are most advanced along one edge. 



Length of largest specimen 2-18 ; diameter at larger end -21 ; at smaller end 

 about -05. 



This species resembles D. venustum, Meek and Worthen, (Proc. Acad. Nat. 

 Sei., Phila., June, 1861, p. 145), from the St. Louis and Spergen Hill lime- 

 stones. The latter, however, tapers but - 075 in one inch, and is described as 

 "nearly" straight and quite smooth, while the present species is rigidly 

 straight and transversely striated. 



PLATYCERAS, Conrad. 



Platyceras cornpforme, n. sp. Shell small, describing about half a whorl, 

 very rapidly enlarging, similarly curved throughout, broadly and obtusely 

 carinated, when young, along the peripheral line ; transverse section becoming 

 subsequently nearly circular ; aperture a little oblique to the whorl, with a 

 somewhat sinuous peristome, the principal sinus being just beneath the mid- 

 dle of the outer lip. Surface marked only by stria? of growth, which curve 

 forwards on the sides, and backwards along a belt just beneath the periphery. 

 The shell is nearly symmetrical and its curvature planorboid. The apex is 

 blunt and not perceptibly turned to the right or left. 



[Jan. 



