INVERTEBRATES. 383 



the existing genus Turritella than any of the Mesozoic or other more modern 

 types, we have concluded to refer it, for the present, to that group, rather than 

 to propose for its reception a new genus, without being able to point out good 

 characters by which it can be distinguished from Turritella. Its lines of 

 growth curve much like those of Loxonema, from all the species of which, how- 

 ever, it differs in its revolving costae. At a first glance it might be mistaken 

 for a Murchisonia, but it certainly differs from that genus in having no trace of 

 a revolving band or labial sinus. 



Prof. Swallow has described, from the Coal Measures at Lexington, Missouri 

 (St. Louis Acad. Sci., 1, p. 203), under the name Murchisonia minima, a very, 

 similar little shell, which may possibly be the same species, unless it really has 

 the sinus in the lip, and the spiral band, of Murchisonia, to which, however, 

 Prof. S. makes no allusion in his description. Dr. Stevens has also described 

 a somewhat similar shell, under the name Aclis minuta, from the Upper Coal 

 Measures at Danville, of this State (Am. Jour. Sci., (2), xxv, p. 259), but his 

 shell differs specifically in the number of its spiral costae. 



Our specific name is given in honor of Dr. R. P. Stevens, of New York City. 



Locality and position: North branch Saline creek, Gallatin county, Illinois; 

 Upper Coal Measures. 



Genus SOLENISCUS, M. and W., 1860. 



(au)X-Qvi<rx.oq, a little channel or gutter.) 

 Soleniscus, Meek and Worthen, Oct., 1860. Proceed. Acad. Nat. Sci., Philad., p. 457. 



Shell fusiform; spire pointed; whorls nearly flat, last one 

 more or less convex in the middle, contracted and produced 

 below into a straight canal ; surface smooth, or only marked 

 by very obscure lines of growth; aperture narrow; outer lip 

 thin and entire; columella straight, imperforate, and provided 

 with one sharply elevated, plait or fold. 



The species constituting the type of this genus bears some analogy to the 

 genus Fasciolaria, but as it differs in having only one nearly transverse fold on 

 the columella, instead of two or three very oblique ones ; while its surface is 

 entirely destitute of nodes, costae, or revolving markings, and its outer lip 

 smooth within, there is little reason for supposing it to be nearly related to 

 that group, which is unknown below the upper Cretaceous. Its texture, 

 smooth surface, pointed spire, shallow suture, and general physiognomy, would 



