1070 THE PALEONTOLOGY OF MINNESOTA. 
[Subulites. 
outer lip thin, the edge straight above, and strongly recurved below, causing the 
lower extremity to be broadly arched in an end view; columella thin, involute, 
terminating abruptly below, above forming a small spiral axial canal; upper whorls 
of spire usually (?always) filled with organic deposit or shut off from the last three 
to five whorls by a deeply concave septum, in consequence of which casts of the 
interior are incomplete above. Type, S. elongatus Conrad. 
As above described, Subulites cannot properly include species like S. calciferus, 
S. psyche and S. daphne of Billings, and S. obesus Whitfield. These agree much 
better with average forms of Fusispira. Of the remaining American species referred 
by authors to Subulites, we remove S. parvulus Billings, S. abbreviatus Hall, S. 
notatus Billings, S. ventricosus Hall, and S. brevis Winchell and Marcy, to our new 
genus Cyrtospira, which see. 8S. richardsoni Billings is not sufficiently known 
to us, but S. inflatus Meek and Worthen is a Fusispira, while S. terebriformis 
Hall and Whitfield, S. gracilis Miller, S. directus Foerste, and S. compactus W hiteaves, 
evidently are good species of Subulites. Of European species, S. attenuatus Lind- 
strom belongs where its describer placed it, but S. priscus Eichwald, as figured by 
Koken, undoubtedly belongs to Fusispira and not to Subulites. 
Of the following species, which, despite the close resemblances prevailing among 
them, are easily enough distinguished when the specimens are reasonably good, we 
are fully satisfied that all, with the possible exception of S. nanus and S. sp. undet., 
are strictly congeneric with S. elongatus. Testiferous examples are extremely rare, 
and good casts of the interior even are not by any means common. Under the 
circumstances it is to be regarded as very fortunate that we have succeeded in 
obtaining specimens showing the form of the aperture of nearly all of the species 
described. Without the aperture it is sometimes extremely difficult to decide 
whether a shell is to be called a Subulites or a slender, flat-whorled Fusispira. If 
the specimen is a cast and is obtusely terminated above as in figs. 1, 2 and 9, on 
plate LXXXI, the observer may be reasonably certain that it belongs to Subulites 
Another apparently constant, at any rate very reliable difference is found in the 
shape of the under side of the whorls. In Fusispira, namely, the lower part of the 
body whorl turns inward more rapidly, causing a stronger concavity in the 
columellar side of the aperture. 
Concerning the systematic value of the characters relied on by us in separating 
the species, we wish to say merely this: if the value of a character is determined by 
the relative constancy of its repetition in individuals, and if it is allowable to assume 
that its value is about the same in all species of the same genus, then the following 
forms deserve to rank as good species. Of only one species have we more than 
fifteen good specimens, namely, S. regularis. These range in length from 40 to 100 
