118 THE CHICAGO ACADEMY OF SCIENCES. 
ventral border of the hinge plate, large, pyramidal, elevated; 
that in the right valve arched, the left angle of the arch being 
shorter than the right, elevated, long, thick; lateral teeth 
double in the right and single in thea left valve, short, elevated, 
stout, but slightly curved; muscle scars very faint; cavity of the 
beaks shallow; nacre bluish or whitish. 
Length, 10.50; height, 7.50; breadth, 5.50 mill. (8510). 
“ 1050; * 8.00; “ 6.00 “ (8510). 
6 90D E es TREO R eo oe ih TO es Carta 
Animal: Not observed. 
Distribution: New England west to California, Canada south 
to Louisiana, Alabama and Florida. 
Geological distribution: Pleistocene. 
Habitat: Same as for stamineum. 
Remarks: This species is closely allied to stamineum 
but may be distinguished by its depressed beaks, more 
elongate outline and fainter growth lines, especially about the 
beak, which is very coarsely sulcated in stamineum. The species 
is as numerous in individuals as the latter species and resembles 
it also in habitat, burying to a considerable depth in the soft 
mud. It is universally distributed. It has been found fossil in 
a sand bank near the lake shore, east of Sheridan Drive and 
north of Graceland Avenue, by Mr. Jensen. 
41. Sphzrium fabale Prime, pl. xxvii., fig. 7. 
Cyclas fabalis Prime, Proc. Bost. Soc. N. H., Vol. IV., p. 159, 1851. 
Cyclas castanea Prime, |. c., Vol. IV., p. 160, 1851. 
Cyclas sulculosa DE CHARPENTIER, MSS, 1851. 
Shell: Of good size, transversely oval, somewhat com- 
pressed, almost equilateral, thin and fragile to quite solid; an- 
terior and posterior margins rounded; ventral margin curved; 
dorsal margin slightly curved; umbones depressed, almost 
flush with the hinge line, placed near the center of the shell 
and quite heavily marked and regular; umbonal slopes gently 
rounded; surface smooth and shining in young or half grown 
specimens but dull in old examples; lines of growth,typically 
very coarse and distinct, but finerin some specimens; color light 
green, yellowish or blackish, the Jatter a marked character in 
old specimens; ligament weak, color varying with the shell; 
cardinal teeth small, those in the left valve unequal, one 
placed near the dorsal margin and extending from the latter 
to a point midway between the dorsal and ventral margins of 
