58 



PROCEEDINGS OF THE ACADEMY OF 



Pamphila iicxEA, nov. sp. 



Expands 1-1 inch. 



Male. Color above and below dark glossy brown ; on primaries an oblique 

 black bar. 



Female. Same color ; on the costa of primaries, near the apex, a yellowish 

 spot divided into three by the nervures, and two small spots near middle of 

 the wing ; all these are repeated below, and on the disk of secondaries are 

 four obsolete points in a transverse line. 



Rock Island, Illinois, from Mr. B. D. Walsh. 



Hesperia vialis, nov. sp. 



Expands 9-10 inch. 



Color fuscous ; the only markings are four fine, yellowish-white spots on 

 costa of primaries near apex ; fringe long, color brown, barred with black by 

 the intersection of the nervures. 



Under side darker, with a purple reflection on apex of primaries and hind 

 margin of secondaries ; thorax grey, palpi light grey. 



Rock Island, Illinois ; Lake Winnipeg. 



Description of a New CARDITJM from the Pleistocene of Hudson's Bay 



BY WM. STIMPSON. 



Cakdium Dawsoni. 



Cardium islandicum Stimpson, (non Chemn.) Proc. Acad. Nat. Sci., Phila., 

 1861, p. 97. 



Shell snbovate, oblique, very inequilateral, and somewhat angular posteri- 

 orly ; beaks small and much elevated ; 

 hinge thin ; teeth weak, especially the pos- 

 terior ones ; ribs about thirty-five in num- 

 ber, in the anterior part of the shell nar- 

 rower than their interspaces, in the mid- 

 dle and posterior parts broader and more 

 flattened ; ventral margin crenated. 



Length 1-63 ; height 1-53; convexity, 

 or breadth, 1 inch. Imperfect specimens 

 indicate a larger size. 



This shell resembles C. islandicum, (cili- 

 atam 0. Fabr.,) in the characters of the 

 hinge, but is easily distinguished by its 

 obliquity and the great elevation of its 

 small beaks, the prominence of which gives 

 an angularity of outline to the umbonial slope, very different from the evenly 

 rounded and more depressed slope of the recent shell. Tha posterior ex- 

 tremity also is much less rounded, and in some specimens the posterior and 

 ventral margins form nearly a right angle with each other. The ribs are not 

 acute as inC. islandicum, but more or less flattened, and generally broader 

 than their interspaces. From C. decorticatum S. Wood, of the English crag, 

 this species differs in its thinner hinge and weak teeth ; from C. inUrruptum 

 of the same author, and formation, by its greater obliquity, and the prominence 

 of the beaks. 



Our specimens all present a character which may perhaps be considered 

 specific ; that of broad concentric bands of erosion, separated by correspond- 

 ing crenulated ridges, indicating periods of arrest of growth in the shell, at 

 which periods the margins, being slowly formed, were of stronger substance 

 than when the deposit proceeded more rapidly. These periods were probably 

 annual, occurring in winter. 



[Feb. 



