998 THE PALEONTOLOGY OP MINNESOTA. 



[Llosptra declplens. 



permitted, we would have illustrated because we expect it will prove a necessary link in showing the 

 evolution of the family. Since it is easily recognized, and as it would facilitate reference to it, we propose 

 to call it Liospira convexa. 



Formation and locality. Vanuxemia bed of the Stones River group, Minneapolis, Minnesota, Dixon, 

 Illinois, and Beloit, Wisconsin. 



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

 Museum Register, No. 687. 



LIOSPIRA DECIPIENS, n. sp. (Ulrich.) 



PLATE LXXXII. FIGS. 39-41. 



Width 18 to 23 mm ; bight 8 to 11 mm.; apical angle about 135; angle formed by slope of spire and 

 outer half of basal slope about 60. Volutions five, flat above from the suture to the sharp, thread-like 

 inner or upper margin of the peripheral band. At least two-thirds of the latter lies upon the upper side 

 of the acute edge of the shell. This portion of the band is distinctly concave and presents exactly the 

 appearance of the entire band of an Eotomaria. When, however, the edge is in good condition, it will be 

 seen that the remaining third of the band turns over the edge and lies, as it should in Liospira, on the 

 under side of the periphery. Excepting the slight elevation of the band, the upper side of the shell forms 

 a smooth even slope, with the lines of growth very obscure. On the under side the umbilicus is covered 

 about as in L. subconcava and L. progne, the forward curve of the lines of growth is only moderate, the 

 mouth transverse, acuminate-ovate. 



The unusual sharpness of the peripheral edge and the distinctly concave character of the upper part 

 of the band are the principal peculiarities of this species. These features will distinguish the species at 

 once from all others now referred to Liospira. At the same time, when the upper side only is visible, one 

 is very liable to mistake the generic position of the shell. 



Formation and locality. Safford's "Central limestone" of the Stones River group, Murfreesboro, 

 Tennessee. 



Confection. E. O. Ulrich. 



LIOSPIRA PERSIMILIS, n. sp. (Ulrich.) 



PLATE LXVIII, FIGS. 45-47. 



In size and general expression, especially in a view on the upper side, this fine shell resembles L. 

 heUna Billings sp. very greatly, but when we turn them over and compare the basal portions, at least one 

 decided difference is quickly observed. Namely, in L. Helena (we have an authentic specimen of this 

 species before us) while the umbilicus is in most cases entirely closed, there is, nevertheless, a small 

 depression, the umbilical region, with the callous reflection of the pillar lip, appearing about as the same 

 part In L. micula and L. progne. In L. persimilis, on the other hand, this region is scarcely, or at any rate 

 less, depressed, while the smooth callosity extends as a thin sheet for a considerable distance beyond what 

 may be properly included in the umbilical region. Among other differences we may mention that the 

 proportional bight of the Canadian shell is as a rule greater, being from two-thirds to three-fourths of the 

 greatest width, while In L. persimilis It varies between one-half and two-thirds. The upper, side of the 

 whorls also Is generally more strongly concave than in our species. Compared with other species L. 

 persimilis is distinguished from all others of the family known to us by the great extent of its umbilical 

 callosity. The next species is closely related. The largest specimen seen is 30mm. In diameter, the 

 smallest 18 mm. 25 or 26 mm. appears to be a fair average. 



Formation and locality. Trenton group, Hartsville, Tennessee, where the seven specimens used in 

 the above description were collected by Prof. J. M. Safford. 



