16 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



162, 1821. BINNEY, Man. Amer. Land Shells, p. 325, 1885. 

 GOULD, Boston Journal Nat. Hist., iii, p. 400, pi. 3, f. 10. 

 PFR., Monogr. Hel. Viv., ii, 357, vi, 329. Bifidaria armifera 

 Say, STERKI, Nautilus, xiii, 1909, p. 52, with var. interpres 

 (p. 52), and varr. similis, affinis and abbreviates (p. 53). 

 WALKER, Occ. Pap. Mus. Zool. Univ. Mich., No. 15, 1915, 

 pp. 5, 9, 10. Pupa armigera Say, POTIEZ ET MICHAUD, Gale- 

 rie des Mollusques, i, 1838, p. 159, pi. 16, f. 1, 2 (Pittsbourg). 

 BINNEY, in Warren's Prelim. Rep. on Expl. in Nebraska 

 and Dakota in the years 1855-57, reprint, 1875, p. 107 (Fort 

 Berthold). 



Eastern United States and Canada: Quebec to northern 

 Florida, west to Bed Deer, Alberta, Dakota, near Boulder, 

 Colorado, Lincoln Co., New Mexico, and the mouth of the 

 Pecos Eiver, Texas. Type locality, Pennsylvania; type no. 

 11624 A. N. S. P. 



This species is easily recognized by its large size, oblong 

 shape, the spermaceti or paraffine tint and large teeth. In 

 life the shell is daubed with dirt. It inhabits almost the 

 whole country east of the continental divide, but is lacking 

 in southwestern New Mexico, southern Texas, southern Flor- 

 ida, and the higher parts of the Alleghany Mountain system. 

 It prefers limestone districts. 



This is much the largest Gastrocopta known. Say's types 

 were not located more exactly than "Pennsylvania". PI. 1, 

 fig. 1 is the type specimen. I select Germantown, Philadel- 

 phia, as the type locality, the specimens from there agreeing 

 exactly with Say's. The columellar lamella, as seen in a 

 view in the back (pi. 1, fig. 3), is most prominent at the 

 lower third. From this prominence a short horizontal branch 

 runs forward (pi. 1, fig. 4), below which the lamella recedes. 

 The peristome is either continued as a thread across the pari- 

 etal wall, or the interruption is short. The usual variation 

 in size, in the type locality, is from 4 to 4.6 mm. long, 2 mm. 

 wide above aperture. The short individuals, having about 

 the same diameter as the long ones, are quite different in 

 contour, being oval, while the long shells are cylindric. 



The basal fold is sometimes distinct, though low, as in pi. 



