NATURAL SCIENCES OP PHILADELPHIA. 119 



i 



Museum of the University of Michigan. Collected by A. Winchell, at Cuya- 

 hoga Falls, Ohio, in the flagstones below the conglomerate. Occurs also in 

 Col. Whittlesey's collection from Akron, Ohio, 50 feet below the conglome- 

 rate. 



This species is distinguished from all other spirifers by the association of 

 cuspidate hinge extremities with a ribbed mesial sinus, and semicircular front 

 margin. When the cuspidations are removed, the shell recalls S. Marionen- 

 sis, Shumard, from the so-called Chemung of Missouri and Iowa ; and, in all 

 except the semicircular outline it corresponds with S. cuspidatus, Hall, (not of 

 Martin, ) from the Chemung of New York. 



Spirifera Sillana, n. sp. Shell transverse, broadest at about the middle ; 

 anterior margin somewhat straight ; ends rounded anteriorly, sub-truncate 

 from the extremity of the greatest diameter to the cardinal side. Dorsal valve 

 of medium convexity, arched regularly from beak to anterior margin ; beak 

 but slightly elevated above the hinge, incurved ; area narrow. A well de- 

 fined mesial fold extends from the beak to the front margin, rising abruptly 

 from the general surface, and arching regularly over. The fold is marked 

 only by incremental lines, save a faint indication of two radial ribs in the 

 vicinity of the umbo ; the other portions of the external surface are marked 

 by one or two imbricating lamellae of growth, and regularly formed ribs which 

 radiate without increase in number, from the beak ; eighteen or twenty of 

 these can be distinguished on each side of the mesial fold. 



Greatest transverse length, 2-1 ; length from beak to anterior margin, 1-05; 

 greatest convexity of dorsal valve, *20 ; width of mesial fold at anterior mar- 

 gin, -45. 



This species is readily distinguished by having an elongate form, without 

 having its greatest length along the hinge line. 



Collected by A. Winchell, at Valley Forge, one and a half miles below Cuya- 

 hoga Falls, Ohio, in fine ferruginous sandstone underlying the conglomerate. 

 Museum of the University of Michigan. 



Named in honor of Judge E. N. Sill, of Cuyahoga Falls, in acknowledgment 

 of facilities afforded the writer in the examination of the rocks of his vicinity. 



Spirifera extenuata, Hall. This Burlington species occurs at Battle 

 Creek, Calhoun county, and Germain's quarry, Hillsdale county, Michigan. 

 Collected by A. Winchell. 



Spirifera hirta ? White and Whitfield. A ventral valve of a spirifer dif- 

 fering from the above only in the absence of all trace of a mesial sinus, and 

 in its somewhat fainter radial lines. 



Bed "No. 6," Burlington, Iowa, while the typical specimens seem to come 

 from Bed "No. 1." "White Collection" of the University of Michigan. 



Spirifera Vernonensis, Swallow, 1860. (Trans. St. Louis Acad. Sci. i. 

 644.) A specimen labelled as above by Dr. B. F. Shumard, from Sulphur 

 Springs, St. Louis county, Missouri, too strongly resembles S. Carteri, Hall, 

 1858, (xth Rep. N. Y. Regents, p. 170,) judging by a specimen of the latter 

 from Cuyahoga Falls, Ohio, which Prof. Hall admitted to be S. Carteri. Coll. 

 A. W. 



Stringothtris Halli, Win. This peculiar form occurs at Battle Creek, 

 Michigan. Collected by A. Winchell. 



SPIRIFERINA, d'Orbigny. 



Spiriferina Clarksvillensis, n. sp. Shell small, transverse, semielliptic, 

 with coarse plications. Ventral valve rather ventricose, most elevated to- 

 ward the beak, regularly arched from beak to anterior margin ; beak broad, 

 projecting much beyond the hinge, strongly recurved ; hinge line nearly as 



1865.] 



