638, THE PALEONTOLOGY OF MINNESOTA. 



[Leperdltella macra. 



is a very distinct species, there is probably not much danger of confusion between 

 thera. 



Formation and locality.— MidAle third of the Trenton shales, Minneapolis, Minnesota. 



Lbpeeditella macra, n. sp. 



PLATE XLin, FIGS. 7-9. 



Size.— ;E. C.) Length 1.4 mm., hight 1.08 mm.; thickness 0.55 mm. 



Carapace short, scarcely oblique, subovate; dorsal margin straight, four-fifths of 

 entire length of carapace, angles distinct; ends subequal, rounding almost uniformly 

 into the basal outline; carapace moderately convex except in the anterior third, which 

 is strongly compressed, giving a very unusual ventral and dorsal profile; anterior 

 edges thicketied, ventral overlap strong; surface smooth. 



This species is remarkable for its compressed anterior part, and for its short 

 form, in neither of which features it is equalled by any leperditoid ostracode known 

 to me. 



Formation and ZocaM%.T— Middle third of the Trenton shales, Minneapolis, Minnesota. 

 Lbpbrditblla gbrmana Ulrich. 



PLATE XLV, FIGS. 24-28. 



Leperditia germana Ulbich, 1892, American Geologist, vol. x, p. 266. 

 Size.— (L. V.) Length 2.17 mm.; hight 1.4 mm.; thickness 0.67 mm. 



Carapace subovate, ends nearly equal, the posterior somewhat the wider; back 

 straight for about four-fifths of the entire length, dorsal angles well marked; ventral 

 outline somewhat oblique, most prominent just behind the center; edges rather blunt, 

 with a narrow groove or rim along the free margins of the left and perhaps of both 

 valves. Surface with the greatest convexity in the posterior half, and a broad, 

 undefined depression in front of the center of the dorsal §lope. 



This form is closely related to L. mundula and L. inflata, two species from the 

 lower division of the Birdseye limestone in Kentucky. From the first it differs in 

 having the ends more equal, the edges blunter, and the surface more convex in the 

 dorsal half. The narrow marginal rim is wanting in that species, and instead of a 

 simple dorsal depression, that form has a low elevation in the lower part of it. The 

 second differs chiefly in the greater inflation of the posterior half of its dprsal region. 



Formation and locality.— This species has so far been met with only in the Lower Blue limestone of 

 the Trenton at Mineral Point, Wisconsin, and Dixon, Illinois, but we know of no reason why it should not 

 occur also at Minneapolis and other localities in the state. 



