282 The American Geologist. May, i80.s 
apex 4 mm.; length of shell lo mm.; width 8 mm.; apical angle, large, 
al)Oiit 90°. 
Formation and locality: The Dresbach at Taylor's Falls in the con- 
glomerate. 
This species is near to T. {Mctopionia) simplex Billings (Pal. Fos., 
\^(j2, vol. 1. p. 346), but is more blunt and full toward the apex. 
Tryblidium aduncum, n. sp. 
Plato XX, Fis.s. 27 and •l>i. 
Shell small, depressed, inclined far forward beyond the anterior 
margin where the apex droops decidedly, and is in two specimens con- 
siderably incurved; the acute apex reaches almost to the plane of the 
base, and the line from apex to anterior margin is sharply concave; pos- 
terior slope is broadly convex, becoming uniformly more convex in 
passing from base to apex; outline from above broadly rounded pos- 
teriorly and sharply acuminate anteriorly; aperture similar to this out- 
line, but less acute in front; surface concentrically striated. Some of 
the specimens referred to this species show in addition a lateral dis- 
placement of the apex. Many others showing all essential characters 
the same are smaller even to one-third the size given. Highest point 
anterior third, 7 mm; hight of apex about i mm; length of aperture 
15 mm; width 12 mm; greatest length of whole shell to apex 20 mm. 
This measurement is from the largest specimen at hand. 
Formation and locality: The Dresbach at Taylor's Falls from the 
marginal conglomerates. 
T, [Metoptoma) crato Billings (Pal. Fos., 1862, vol. I, p. 39), 
the nearest described species to this form, also shows this lateral 
tendency, but is of very different proportions and from a later forma- 
tion. 
G.-nus Hypseloconus, new genus. 
Et,viiii)l(«.v : hijjweloN. liijili, and fcoiio.s, a cone. 
A large number of specimens have been secured which are of the 
general type represented hy ilfe/op/oma rccurTUi Whitfield* A study of 
these forms side by side with those of the Try fi/i;/m»i type and others has 
convinced me that they belong to a new genus. The variation in 
these recurved forms leads to a very different line of development. 
For example in the Tryblidiii'in type, a morphologic series may be 
arranged in which the forms are more and more depressed at the 
apex and more convex on the posterior slope but not developing a 
coil. In the proposed genus, on the other hand, the series passes by 
easy steps, in which not a single member is missing, to a coil of the 
Eccylioinphahis type. In Tryblicihiin the apex inclines toward the 
narrower margin of the aperture while in Hypseloconus it coils toward 
the broader margin. 
With the excellent material at hand it has been found practicable 
to group all these forms which curve toward the broader margin of 
■''Geol. Wis., vol. IV, p. 196, plate 3, figs. 14 and 15. 
