1070 THE PALEONTOLOGY OF MINNESOTA. 



ISubulltes. 



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. 8. 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 Whiteaves, 

 evidently are good species of Subulites. Of European species, S. attenuates Lind- 

 strom belongs where its describer placed it, but S. prisons 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 f ally 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 



