NATURAL SCIENCES OF PHILADELPHIA. 127 



acuniiiiately tapering toward the opposite extremity. Anterior side nearly 

 straight, or distinctly hollowed. Posterior side parallel with the anterior for 

 half its length ; toward the hinge gradually approaching the opposite side. 

 The truncation is at right angles with the anterior side, leaving a broadly 

 gaping ventral margin. External surface smooth. 



Length dorso-ventrally "97 (100) ; greatest dimension at right angles with 

 this -26 (27) ; thickness of both valves -12 (12). 



Collected by A. Winchell at Napoleon cut, Jackson County, Michigan. 



MYALINA, DeKoninck. 



Myalina Lowensis, n. sp. Shell rather small, ventricose, obliquely elon- 

 gate-quadrate. Umbonal ridge elevated, arched, highest about midway be- 

 tween the beak and the opposite end, forming an angle of 50 with the straight, 

 somewhat elongate hinge line ; anterior and posterior sides parallel, the former 

 distended in a very shallow pouch just beneath the beak, the latter very 

 slightly hollowed throughout its upper half ; basal region regularly rounded, 

 with an obtuse angulation next the posterior side. From the umbonal ridge 

 the slope is precipitous to the anterior margin, much less so toward the pos- 

 terior, and it gradually subsides into a flattening toward the dorso-lateral 

 angle. Surface of shell nearly smooth, marked with fine incremental lines. 



Greatest dimension from beak to opposite extremity - 83 (100) ; length of 

 hinge line *46 (55) ; diameter, at right angles with umbonal ridge, "41 (50). 



From the base of the Burlington limestone. "White Collection," of the 

 University of Michigan. 



This species resembles M. angulata, Meek and Worthen, from the Chester 

 limestone of Illinois, and M. Michiganensis, Winchell, from the Marshall group 

 of Michigan. From the former it differs greatly in its smaller size, its shal- 

 lower posterior concavity, and its less abruptly rounded base. From the 

 latter it differs in having straighter anterior and posterior sides, giving it a 

 more quadrate outline, a more elevated umbonal ridge, and a shorter antero- 

 posterior dimension. 



Myalina Michiganensis, Win. Collected by A. Winchell at Napoleon Cut, 

 Jackson County, and at Germain's Quarry, Hillsdale, Hillsdale County, Mich. 



Edmondia ? bicarinata, Win. A species apparently identical with this 

 occurs in a conglomerate four miles north of Panama, Chataque County, New 

 York, supposed by Prof. Hall, in his Report on the Fourth District of New 

 York, to constitute a portion of the Millstone Grit of Pennsylvania. It was 

 figured and briefly characterized under the name of Cypricardia contracta, 

 Hall. The later specific name must therefore be abandoned. 



Edmondia jequimarginalis, Win. Specimens clearly identical with this 

 occur in the same conglomerate with the above, as also in a conglomerate at 

 another locality, supposed by Prof. Hall to underlie the Millstone Grit, and 

 to constitute the terminal member of the Chemung Group. 



The specimens of these two species occurring in New York, as well as the 

 two others to be mentioned, are preserved in Prof. Hall's cabinet ; and I desire 

 to acknowledge my great obligations for the opportunity afforded of making 

 the direct comparisons. 



Edmondia Burungtonensis ? White and Whitfield. A lamellibranch, too 

 imperfect for certain determination, but closely resembling the above, occurs 

 in Whittlesey's Collection, from a place "one mile east of Orange Center, 

 Cuyahoga County, Ohio, 25 or 30 feet below the Grindstone Grit." 



SANGUINOLITES, McCoy. 



Sangdinolites sthigatcs, n. sp. A small species, resembling Area modesta 

 Win., from Burlington, Iowa. Unfortunately the specimen was lost while 

 awaiting a description. It had, however, been investigated and its generic 



1865.] 



