1036 THE PALEONTOLOGY OF MINNESOTA. 



[Hellcotoma declivis. 



HELICOTOMA DECLIVIS Safford. 



PLATE LXXIV, FIGS. 31-38. 



Helicotoma declivis SAFFOED, 1369, Geol. of Tenn., p. 288. (Neither defined nor illustrated.) 



This species is remarkable especially for two reasons: first, the umbilical cavity, which is rather 

 wide,- has even slopes on which the inner whorls are more or less obscurely or quite indistinctly defined ; 

 second, the upper surface of the whorls is raised so as to form a broad, obtuse, median angulation or ridge. 

 The inner whorls of the spire are depressed slightly beneath the level of the outer one while the notch- 

 carina is so small that it fails to rise to the level of the median ridge. 



Formation and locality. Associated with H. tennesseensis in the lower part of the Stones River group 

 at Murfreesboro, Tennessee. 



Collections. Prof. J. M. Safford ; E. O. Ulrich. 



HELICOTOMA MAKGINATA, n. sp. (Ulrich) 



PLATE LXXIV, FIG. 39. 



Of this species we have seen but the unique example of which a view of the upper side is given on 

 plate LXXIV. It is remarkable chiefly because the lower part of the outer side of its whorls is so promi- 

 nently developed that it projects like a broad flange. 



Formation and locality. Found at the extreme top of the Richmond group, Elkhorn falls, near Rich- 

 mond, Indiana. 



Collection. E. O. Ulrich. 



Genus ECCYLIOMPHALUS, Portlock. 



Eccylfomphalus, PORTLOCK, 1843, Geol. Rep. Lond., p. 411. 



For remarks on this genus see pages 1024 and 1029. 



ECCYLIOMPHALUS UNDULATUS Hall. 



PLATE LXXV, FIGS. 19-23. 



Ecculiomphalus undulatus HALL, 1861, Geol. Rep. Wis., p. 37 ; WHITFIED, 1895, Mem. Am. Mus. Nat. 

 Hist., vol. i, pt. 2, p. 63, plate VHI, flgs. 13. 



Original description. "Shell consisting of one or two volutions, spirally coiled, but distantly separated 

 from each other, rapidly increasing in size from the apex, and of asubtriangular or ovate-triangular form, 

 the upper side being convex and curving to the ventral margin; the dorsum is somewhat flattened, and 

 the lower side sloping with a gentle curve from the lower lateral angle to the ventral side, which is narrow 

 and sharply rounded. Along the ventral side and a little below the center there is a narrow, abruptly 

 depressed groove, which extends the entire length of the shell. 



"Surface of the shell marked by obscure undulations, which are most distinct on the lower lateral 

 angle, also on the lower side by two or three revolving ridges.* Fine transverse lines of growth parallel 

 to the margin of the aperture are visible over the greater part of the surface of the specimen, which is 

 essentially a cast of the interior." 



To the above description we may add that there is a broad sinus in the upper part of the mouth, 

 and that the depressions on the outer side of the shell are due to agglutinated foreign objects like fragments 



We do not understand what Is meant by the "two or tbree revolving ridges" on the lower side, sluce we have not 

 observed anything of the kind on our specimens. That the latter are specifically Identical with H all's species we are 

 confident after seeing Whltfleld'n figures of the original type (luc. ctt.). 



