1004 THE PALEONTOLOGY OF MINNESOTA. 



Eotomarla supraclngulata. 



turretted." In the Stones River specimens the last feature is not apparent and the spire is more 

 depressed, giving an apical angle of about 110. 



Formation and locality. Stones River group, Vanuxemia bed, Minneapolis and Cannon Falls, Min- 

 nesota. Black River group, Maury county, Tennessee. 



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



EOTOMARIA SUPRACINGULATA Billings. 

 PLATE LXIX, FIGS. 26-29. 



Pleurotomaria supracingulata BILLINGS, 1857, Rep. of Progr., Geol. Sur. Can., p. 302 ; 1863, Geology of 



Canada, p. 181, flg. 175. 

 Pkurotomaria nasoni HALL, 1861, Geol. Rep. Wis., p. 34 ; WHITFIELD, 1895, Mem. Amer. Mus. Nat. 



Hist., vol. i, pt. 2, p. 61, pi. vin, flgs. 4-7. 



Raphistoma nasoni WHITFIELD, 1883, Geol. of Wis., vol. Iv, p. 215, pi. vi. flgs. 2-3. 

 Raphistoma nasoni WALCOTT, 1884, Pal. Eureka District, p. 78, pi. xr, flgs. 21, 21a. 



Original description. "Obtusely conical or lenticular, apical angle 105; hight about two-thirds the 

 width; whorls four, angulated and keeled on their upper outer margin, their sides vertical, their upper 

 surfaces gently convex from the distinct suture half-way to the margin, and then scarcely concave to the 

 spiral band ; lower side of body-whorl convex ; the spiral band narrow, and lying wholly on the upper 

 side of the whorl, where it forms a border along the margin following all the whorls to the apex ; umbili- 

 cus large; width one inch and a quarter; hight ten lines; width of umbilicus at center of body-whorl 

 three lines and a half ; width of band on last whorl about half a line." 



To the above we may add that the lines of growth are generally not strongly marked, and when 

 they are distinct it is only on the lower side of the last whorl of old shells. On the best specimens they 

 consist of obscure undulations, from 1 to 2 mm. apart, with four or five very fine lines between any two 

 undulations, all curving backward on the upper side in the usual manner and degree. Beneath the 

 band, however, the lines make a sharper and longer sweep forward than in any pleurotomaroid shell 

 known to us. Just before reaching a point midway between the band and the obtuse edge of the umbili- 

 cus they begin an almost equally strong backward curve, which in turn is overcome as they enter the 

 umbilical depression on the sides of which they bend once more, this time gently forward. In accordance 

 with the lines of growth, the aperture is very deeply notched and the outer lip greatly produced, the most 

 prominent point on its narrowly rounded anterior outline extending slightly beyond the sutural extremity 

 of the upper lip, while the lower lip Is broadly and rather deeply sinuate. These features of the aperture 

 are shown in our figures 27 and 29 on plate LXIX. The band Is sharply defined and concave on the 

 exterior of the shell, rounded or obscurely flattened on casts of the interior. The outer side of the whorls 

 is never quite vertical, nor is the band horizontal. The latter slopes with the spire. The largest speci- 

 men seen is 43 mm. wide and about 27 mm. high. 



That Pleurokmaria nasoni Hall is a synonym for PI. supracingulata Billings is so obvious that we 

 cannot understand why the fact was not discovered years ago. Perhaps it is because one was described 

 from a testiferous specimen, while the other was founded on casts of the interior. Another thing that 

 we cannot understand is how Prof. Whitfleld can say that "this shell appears to possess all the features 

 requisite for a true Raphistoma.'" So far as we can see it has not one of the essential characters of that 

 genus. There is some reason for calling the species a Pleurotomaria, but none that we can discover for 

 placing it with Raphistoma. Excepting the unusual prolongation of the outer lip, and this is not an 

 insuperable objection, every feature conforms strictly with our genus Eotomaria. 



Formation and locality. Stones River group, Dixon, Illinois; Mineral Point and Beloit, Wisconsin. 

 Black River group (Upper Buff limestone), Beloit and Jancsville, Wisconsin ; Rockton and Dixon, Illinois ; 

 St. Joseph island, lake Huron. According to F. W. Sardeson this species occurs in the Vanuxemia bed 

 at Minneapolis. 



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



Museum Register, No. 7296. 



