974 THE PALEONTOLOGY OF MINNESOTA. 



[Lopbosplra medialis. 



Nearly intermediate between L. perangulata Hall and L. sororcula Billings sp., 

 having a small umbilicus and depressed volutions like the former and a hight of 

 spire and general appearance more like the latter. The convexity or obscure 

 angulation of the upper part of the volutions, as well as the lesser development of 

 the lower carina, distinguishes it from both and suggests relationship with L. oweni 

 and L. ampla. 



Formation and locality. Rare in the Trenton group of Minnesota, in the Clitarnbonites bed at St. 

 Paul, and the Fusispira bed at Wykofl; common in the upper beds of the Trenton between Burgin and 

 Danville and at other localities in Kentucky; occurs also in middle Tennessee and in Lincoln county, 

 Missouri. 



Collection. E. O. Ulrich. (45 specimens.) 



LOPHOSPIRA MEDIALIS, var. BURGiNENSis, n. var. (Ulrich.) 



PLATE LXXIII. FIGS. 30 and 31. 



Hight 10 to 14 mm., apical angle almost constantly 60 ; volutions six. 



Agrees in all respects with M. medialis excepting that the average size is less, 

 and the lower carina much stronger and more prominent. The lower carina causes 

 also a flattening of the base that does not occur in the typical variety. 



Var. burginensis, having a small umbilicus, must still remain separate from the 

 Quebec group L. sororcula Billings. It resembles very greatly also L. pulchella, but 

 has a wider apical angle, while the subsutural or upper carina is never well defined 

 as it is in that species. In L. perangulata the apical angle is somewhat narrower, 

 the slope of the upper side of the whorls less steep, and the space between the 

 peripheral and lower carinse more nearly vertical and less concave. 



Formation and locality. Opper part of the Trenton group, Burgin, Danville, Lexington and other 

 localities in Kentucky. 



Collection. E. O. Ulrich. (35 specimens.) 



LOPHOSPIRA ABNORMIS, n. sp. (Ulrich.) 



PLATE LXXIII, FIGS. 36-40. 



Hight 15 to 20 mm.; apical angle increasing with growth from 42 to 53; 

 volutions six or seven. 



The size, surface markings, umbilicus and form of the volutions is almost 

 exactly as in L. medialis, and if the last two whorls only were compared it would 

 be most difficult to distinguish them, Still, a comparison of interior casts, the 

 condition in which L. abnormis is usually found, will show that in the present 

 species the umbilicus is less abrupt and the peripheral angle of the whorls more 

 prominent and situated lower down, causing the upper slope to be slightly wider, 

 higher and more convex. Besides the casts show an obscure revolving line or ridge 



