1078 THE PALEONTOLOGY OF MINNESOTA. 



IFusispira nobllis. 



more depressed and more convex, the result being a deeper suture; the aperture is relatively wider and not 

 so high, the length being but little more than twice the greatest width; and, if we may depend upon the 

 appearance of the suture in casts, the test must have been thicker, though perhaps not greatly so. One 

 of the specimens (pi. LXXX, fig. 8) exhibits four or five obscure revolving furrows on each of the two lower 

 whorls. These probably indicate even closer relations with F. schucherti, F. sulcata and F. nobilis, but we 

 doubt if any one will be likely to confuse the present species with any of those. F. terebriformis Hall is a 

 more slender shell and has a longer aperture. 



There may be some doubt concerning the specific identity of the two specimens referred to this 

 species on plate LXXX. The larger, which is from Cannon Falls, Minnesota, retains only the mouth and 

 a part of the last two whorls. As near as we can judge from these the apical angle was several degrees 

 narrower than in the specimen from Trenton Falls, New York. In other respects, however, the two agree 

 very well. 



Formation and locality. Trenton group, Trenton Falls, New York; Clitambonites bed, near Cannon 

 Falls, Minnesota. 



Collection. E. O. Ulrich. 



FUSISPIRA NOBILIS, . Sp. 

 PLATE LXXX, FIGS. 2-4. 



Shell attaining a bight of 100 mm. and a width of 34 mm., the aperture in such a specimen having a 

 bight of about 44 mm.; apical angle 27 to 30; whorls six or seven, gently convex, the last sloping rather 

 abruptly inward at the base; aperture acuminate above, narrowly rounded below, somewhat lozenge- 

 shaped in outline, widest in the middle, the length slightly greater than twice the width; surface of cast 

 sometimes showing about seven faint revolving lines on each whorl; test apparently very thin. 



The apical angle is wider, the body whorl more abruptly contracted, and the whorls in the spire less 

 convex than in F. subfusiformis. F. convexa has much more convex and more depressed whorls. In F. 

 schucherti and F. sulcata the shell is much thicker, while in F. planulala the whorls are almost perfectly 

 flat. None of the other species are very closely related. 



We are indebted to Dr. C. H. Bobbins, of Wykoff, Minnesota, for the best specimen seen by us. 



Formation and locality. Fusispira bed of the Trenton group, Wykoff, Pleasant Grove and Fountain, 

 Minnesota. 



Colkctions. Geological and Natural History Survey of Minnesota; E. O. Ulrich. 

 Museum Register, No. 7331. 



FOSISPIKA PLANULATA, M. Sp. 

 PLATE LXXXI, FIGS. 26 and 27. 



This species resembles, and doubtless is closely related to, F. nobilis, but a critical comparison 

 brings out several good differences. It probably did not attain the size of that noble shell, while the spire 

 is more slender the apical angle is only 21 as against 27 or more in F. nobilis and forms almost an even 

 cone, the whorls being quite flat and the suture, even in the cast, very slightly impressed. The base of 

 the body whorl also turns inward even more abruptly, the junction between the base and outer side being 

 obtusely angular rather than sharply rounded. 



Formation and locality. Fusispira bed of the Trenton group, Wykoff, Minnesota, where we obtained 

 a single example. It is of smaller size than the illustrated specimen, which we collected some years ago 

 in apparently equivalent strata at Eagle Point, Iowa. 



Collection E. O. Ulrich. 



