GASTROPODA. 1075 
Fusispira.] 
Genus FUSISPIRA, Hall. 
In part Murchisonia and Subulites of several authors. 
Fusispira, HALL, 1871, Twenty-fourth Rep. N. Y. St. Mus. Nat. Hist., p. 229. 
Shell fusiform, spire elevated; whorls generally convex, with distinct sutures, 
at other times nearly flat with shallow—or enamelled—sutures; aperture longitu- 
dinal, elongate ovate or subelliptical, acuminate above, produced below, forming a 
subrimate canal; outer lip sharp, its edge straight from the suture almost to the 
involute extremity of the columella; columella nearly vertical, slightly twisted, 
simple, thin; test varying in thickness, sometimes heavy with indications of broad 
revolving bands (?color bands); exterior surface smooth, or with rows of minute 
punctures arranged in either revolving or longitudinal lines. Type, I’. ventricosa 
Hali, which seems to be a variety of F’ inflata Meek and Worthen sp. 
The principal difference between this genus and Swhulites, Conrad, lies in the 
basal part of the aperture. This is ‘relatively wider and more truncated in that 
genus. On page 1070 we give other details that may aid the student in discrimi- 
nating between the two genera. These may be supplemented with the remark that 
the shell is perhaps always heavier in Fusispira, giving deeper and open sutures in 
clean casts of the interior. 
Fusisprra INFLATA Meek and Worthen. 
PLATE LXXX, FIGS. 17 and 18. 
Subulites inflatus MEEK and WORTHEN, 1870, Proc. Acad. Nat. Sci. Phila., p. 47; also 1875, Geol. Sur. 
Ill.. vol. vi, p. 495. 
Fusispira ventricosa HALL, 1871, Twenty-fourth Rep. N. Y. St. Mus. Nat. Hist., p. 229, pl. vm, fig. 6; 
WHITFIELD, 1882, Geol. Wis., vol. iv, p. 245, pl. 1x, fig. 2. 
Casts of the interior comparatively short-fusiform, ventricose, consisting of six or seven convex 
whorls, the apical angle expanding with each whorl after the third or fourth; average apical angle about 
60°. Volutions strongly convex, the last very ventricose and constituting over two-thirds of the entire 
hight of cast; under side of whorls, as seen along the whole inner side of the aperture, strongly concave, 
the upper half of the outline meeting the vertical lower or columellar half at an angle of about 135° in the 
typical form and about 125° in the variety ventricosa; suture distinct without being channelled or 
impressed: Aperture oblique, narrow, the length more than twice the width and a little more than half 
of the entire length of the cast; base abruptly rounded, forming a shallow canal; outer lip sharp, directed 
slightly forward in the middle; columella vertical, nearly straight, less than half the length of the aper- 
ture, very slightly twisted. Surface of casts smooth, of the shell unknown. 
This species is very constant in most respects, and yet a recognizable and apparently persistent dif- 
ference obtains between the specimens of the Fusispira bed and those of the overlying Maclurea bed. In 
the latter, namely, and these agree most closely with the Wisconsin types of F. ventricosa, the under side of 
the body volution is slightly more ventricose and rounds in more abruptly where it joins the columella, 
forming a deeper angle than in the typical form of the species. In Hall’s figure, however, the angle is 
deeper than we have seen it, and, considering the constancy of the part in other specimens, we are inclined 
to believe that it was drawn deeper than it should be. 
Formation and locality.—Rather common in the Fusispira bed at Hader, Aspelund, Wykoff and other 
localities in Goodhue and Fillmore counties; also in the Maclurea bed (var. ventricosa) at Sumner, Stew- 
