GASTROPODA. 971 
Lophospira helicteres.] 
LOPHOSPIRA HELICTERES Salter, var. WISCONSINENSIS, 7. var. 
- PLATE LXXTI, FIGS. 25—28. 
Murchisonia helicteres SALTER, 1859, Can. Org. Rem., Dec. 1, p. 21, pl. rv, figs. 2--4. 
Murchisonia helicteres et tricarinata (part. ) WHITFIELD, 1882, Geol. of Wis., vol. iv, pp. 219 and 220. 
Hight 28 to 68 mm.; apical angle of upper volutions 58° to 65°, of entire full 
grown shell 40° to 45°. Volutions five or six, of which the first three or four are 
closely coiled and the last one or two, or even three, are free and widely separated. 
The free whorls are marked on the exterior by five keels, the uppermost being the 
least distinct and representing the suture line; the second is stronger and in the 
upper part of the shell situated almost midway between the suture line and the 
peripheral angle, but after the whorls become free it is moved relatively much 
nearer the sutural edge; the third or peripheral carina is the strongest and most 
prominent, and bluntly or rounded flat, or even concave at the edge; above it the 
surface is decidedly concave, beneath it for the greater part to the fourth carina 
almost flat; the latter is situated about the same distance from the central keel as 
the second but is scarcely as strong; the fifth keel is relatively weak and situated 
on the base of the whorl. Surface with distinct, sharp, equidistant lines of growth 
averaging eight or ninein5 mm. Their course from the suture to the peripheral 
angle is almost direct, as itis also from here to the basal keel. Near and on the 
peripheral keel a more or less abrupt retral curve occurs, indicating an unusually 
restricted notch in the outer lip of the aperture. 
In casts of the interior the two upper carinz appear as very near each other, 
yet distinguishable as far up the spire as the third or even the second volution. 
The peripheral angle, though gradually losing its prominence, may be recognized 
on all the whorls. The fourth is but rarely distinguishable, the fifth, never. 
The above describes the main characters of the Wisconsin and Minnesota 
variety of this species. As may have been noticed, it differs in two respects from 
the typical Canadian form, namely, (1) the surface striz are more regular and much 
less curved backward in consequence of which the insinuation in the outer lip of 
the aperture is relatively very small; second, they have a basal or umbilical keel 
(similar to the one in ZL. serrulata) which is wanting in the typical variety. The 
latter occurs not only in Canada but in central Kentucky as well, while the var. 
wisconsinensis is, so far as known, restricted to the northwestern area. 
This fine Lophospira, though really widely different, greatly resembles, in the 
usual condition in which they occur, the preceding species, L. serrulata. Both are 
strongly carinated and have the last whorls free, while the surface striz also are 
similar in being strong and sharp in both. Still, when the shells themselves, or good 
molds of their exterior surface, could be compared, we found little difficulty in 
