380 PALEONTOLOGY OF ILLINOIS. 



gin of the lip ; just below the suture these lines are gathered 

 into a series of minute, short, regularly arranged wrinkles or 

 crenulations, scarcely visible without the aid of a lens. Length, 

 0.70 inch; breadth, 0.24 inch; length of aperture, 0.18 inch; 

 breadth of do., 0.11 inch. Apical angle regular, divergence 24°. 



In some respects this species is closely allied to Chemenitzia sulconstricta, 

 de Koninck (/Smjj. An. Foss., pi. lviii, p. 17), particularly in form, and the 

 peculiar minutely wrinkled or crenulated character of the upper margin of its 

 whorls. It differs, however, in the form of the aperture, which is more quad- 

 rangular, and less produced below, than de Koninck's species, and the columella 

 is also straighter. The lip of our specimen being broken, may give an unnatu- 

 ral appearance to the base of the aperture, but it certainly looks very much as 

 if there had been a small oblique notch at the end of the columella, as we see 

 in Cerithium. If this is natural it can scarcely be a true Loxonema. 



Locality and position : Springfield, 111. ; Upper Coal Measures. 



Genus ORTHONEMA, M. and W. 



(Etym. — op&oq, straight; vvjp.a, a thread.) 

 Orthonema, Meek and Worthen, June, 1861. Proceed. Acad. Nat. Sci., Philad., p. 146. 



Shell elongate, many-whorled ; volutions ornamented with 

 revolving carinae, crossed by nearly straight lines of growth ; 

 body whorl generally angular, not much enlarged or produced 

 below ; aperture angular above, slightly effuse below ; peri- 

 stome incomplete ; outer lip simple, nearly straight ; axis im- 

 perforate. 



The shell upon which we proposed to found this genus has much the appear- 

 ance of a Murchisonia, but differs in being entirely destitute of a spiral band, or 

 a sinus in the lip, as in that genus and Pleurotomaria — the lines of growth 

 being distinctly seen crossing the carinae, and the spaces between, without 

 making the slightest curve. In first indicating the typical species of this genus, 

 we referred it, with a query, to Mr. Salter's genus Eunema; later comparisons, 

 however, have satisfied us that it cannot be properly placed in that group, since 

 it does not possess the peculiar sigmoid lip characterizing the forms described 

 by Mr. Salter. It also differs in having its whorls closely contiguous at all 



