1052 THE PALEONTOLOGY OF MINNESOTA. 



[Trochonema nlota. 



TROCHONEMA NIOTA Hall. 



PLATE LXXVI. FIGS. 1618. 



Pleurotomaria niota HALL, 1861, Geol. Sur. Wis. Rep. Prog., p. 33; WHITFIELD, 1895, Mem. Amer. Mus. 

 Nat. Hist., vol. i, pt. ii, p. 60, plate vn, fig. 11. 



Original description." Shell large, broadly subconical, the diameter through the last volution equal 

 to about four-fifths of the bight, consisting of six volutions, which are flattened on the periphery, with a 

 very slightly concave space upon the upper side, extending to the suture; lower side rounded into the 

 moderately large umbilicus, the last volution large and ventricose. 



"Surface character unknown, except a few undefined undulations near the extremity of the last 

 volution, which are more distinct below than above." 



The above description is not very clear, and as Hall compares the species with his Pleurotomaria 

 subconica and P. bicincta, saying that it is intermediate in form between them, we naturally failed to 

 recognize the form until Whitfleld (toe. cit.) figured the original type The specimen illustrated by us evi- 

 dently is in better condition than the type, and shows clearly that it has no affinities with the two species 

 with which Hall compares his specimen. It is nothing more nor lesc than a high-spired Trochonema, with 

 a very small umbilicus for this genus. The upper slope of the whorls is more concave than shown in 

 Whitfleld's figure. The lower lip was broadly sinuated, the inner almost vertical, while the shell appears 

 to have been thin and the surface markings not very strong. 



Formation and locality. Butt limestone (? Stones Elver group), Beloit, Wisconsin, where the speci- 

 men here used was collected by Mr. H. C. Powers. 



Collection. E. O. Dlrlch. 



TROCHONEMA ALTUM, n. sp. 



PLATE LXXVII, FIGS. 3941. 



The cast of the interior figured on plate LXXVII is all we have seen of this species. It evidently 

 represents a Trochonema with an unusually high spire, minute umbilicus, wide peripheral band and 

 slightly convex rather than concave upper slope. In some respects it reminds one of T. niota Hall sp., but 

 has a wider peripheral band, more rounded whorls, and seems to have been a much smaller shell. We 

 know of no other species near enough to require comparisons. 



Both T. altum and T. niota form relatively high shells, and might therefore be referred to the sub- 

 genus Eunema, but as their mouths are oblique we think it best to leave them in the typical section of 

 the genus. 



.Formation and locality. Lower half of Fusispira bed, Trenton group, near Cannon Falls, Minnesota. 

 Collection. E. O. Ulrich. 



Subgenus EUNEMA, Salter. 



Eunema, SALTEB, 1859, Canadian Organic Remains, Dec. I, pp. 24 and 29. 



This term may be employed provisionally as a subgeneric designation under 

 Trochonema. As denned on p. 1046, it will include, besides the type, E. strigillatum 

 Salter, the following six species. In none of the latter is the spire as high as in 

 Salter's species, but all have about the same kind of mouth, and that we deem of 

 more consequence than either the bight of the spire or the size of the umbilicus. 

 E. pagoda Salter and E. vrisca Billings are widely different, being Pleurotomariidce 

 (see p. 1021). 



