OEETACEOUS PERIOD. 193 



angle distinct upon the body-volution, and foiTns a carina as it is continued 

 out upon the spine-like posterior process of the wing. This process 

 diverges widely from the axis of the shell, and curves gently backward ; 

 anterior process of the wing moderately large, linguliforai, projecting 

 straight outward, and a little forward, and separated from the other process 

 by a notch of moderate width, which is abruptly rounded at the bottom. 

 From the base of the spine-like process, the posterior border of the wing 

 curves gently inward and backward against the spire ; anterior border of 

 the wing curving forward from the base of the anterior process and ending 

 in the slender anterior canal ; posterior canal or groove narrow, extending 

 back nearl}^ or quite to the apex of the spire. Surface of the wing marked by 

 the ordinary lines of growth, and upon the outer volution of some speci- 

 mens there are faint indications of revohang strise. 



Full length of the shell, froni the apex to the end of the anterior canal, 

 about thirteen millimeters ; width across the last volution, including the 

 whole wing, but not the processes, six millimeters. 



This species is closely related to L. nuptialis of the preceding descrip- 

 tion, but differs from that species in its less robust form, comparatively 

 smaller wing, more slender and less recurving posterior process, and in the 

 lingulifonn, instead of lobe-shaped anterior process. 



Position and locality. — Strata of the Cretaceous period ; east of Mount 

 Taylor, one mile south of Pajuate, New Mexico. 



Family TECTURIDiE. 



Genus ANISOMYON Meek and Hayden, 1860. 

 Anisomyon borealis Morton, s}}- 



Plate XVIII, fig. 9 a and h. 



Hippojigx borealis Morton, 1842, Jour. Acad. Nat. Sci. Pbila., viii, pi. ii, fig. G. 

 Jlelcion carinatus Meek and Hayden, 1856, Proc. Acad. Nat. Sci. Phila., 68. 

 Anisomyon iorealis Meek and Hayden, 1860, Am. Jour. Sci., sxviii, 2d s., 35. 



Shell obliquely conical ; marginal outline broadly oval or suboval ; 

 breadth greater than the height ; lateral slopes nearly straight or slightly 

 convex ; anterior slope concave ; posterior slope convex. Surface marked 

 13 F 



