GASTROPODA. 841 
Scenella obtusa.] 
Metoptoma montrealensis Billings, and Tryblidium conicum Whitfield, but neither of 
these species has the anterior slope sharply rounded as in S. affinis and S. compressa. 
Whitfield’s species, which we regard as a true Scenella, seems to be more closely 
related to S. superba and S. beloitensis than to S. montrealensis. The latter, judging 
solely from Billings’ figures and description (op. cit.), appears to differ from all the 
species mentioned in having a more attenuate apex and the whole anterior outline 
concave in a side view. 
Besides the typical specimens of S. afinis we have before us six others from 
the geologically higher Clitambonites and Fusispira beds. In these the anterior 
vertical ridge is less developed and the outline of the apertyre more regularly 
elliptical. The shell also seems to have been thinner and smoother externally. If 
a subordinate name is desired for this later form of the species it might be called 
var. obsoleta. 
Formation and locality.—Black River group, Ctenodonta bed, and Trenton group, Clitambonites 
bed, Goodhue county, Minnesota; Fusispira bed, Kenyon and Wykoff, Minnesota. 
Collections—Geological and Natural History Survey of Minnesota; HE. O. Ulrich; W. H. Scofield. 
Museum Register, No. 7487. 
SCENELLA OBTUSA Sardeson. 
PLATE LXXXII, FIG. 10. 
Conchopeltis obtusa SARDESON, 1892, Bull. Minn. Acad. Nat. Sci., vol. iii, p. 336. 
Having seen no specimens which we could refer to this species, we reproduce 
the original figure and description without expressing any positive opinion as to its 
validity. So far as Mr. Sardeson’s figure of the specimen upon which he founds the 
species permits of judgment, it seems to us to be a Scenella in which the apex is 
farther removed from the center and the apical angle wider than usual. 
Original description: “Shell large, patelliform, or subconical, apex excentric, 
apical angle 110 degrees. Aperture subcircular, about three times as wide as the 
shell is high. Cast marked by four or five concentric furrows and by numerous 
elevated radiating lines, from 15 to 20 in one centimeter.” 
Formation and locality.—Black River group, Rhinidictya bed, Minneapolis, Minnesota. 
SCENELLA RADIALIS, 7, Sp. 
PLATE LXI, FIGS. 31 and 32. 
Shell large, depressed conical, hight slightly greater than one-third of the 
diameter; apex subcentral, obtuse; aperture almost circular, the margin apparently 
a little irregular-though nearly horizontal. Surface with distinct lines radiating 
from the apex, five orsixin5 mm. These show through the outer parts of the 
