76 PROCEEDINGS OF THE ACADEMY OF 



but its body part is much straighter, while it is never so large 

 and ventricose as in some varieties of that species. 



Locality and position. Columbus, Ohio. Corniferous group. 



NATICOPSIS LEVIS, Meek. 



Shell apparentl}^ attaining a medium size, subovate in general 

 form, at maturity, but pi-oportionally shorter in the young; 

 spire moderately prominent ; volutions four to four and a half, 

 convex, increasing rather rapidly in size ; last one large, or form- 

 ing near nine-tenths of the entire bulk of the shell, rounded on the 

 sides, and a little extended below; suture well defined; ajierture 

 ovate, being regularly rounded below, and more or less angular 

 above; columella arcuate, and distinctly flattened, or a little 

 concave below the nou-perforate umbilical region, above which the 

 inner lip is thickened. Surface only showing obscure lines of 

 growth. 



Length of the largest specimens seen, 0.60 inch ; breadth, 0.48 

 inch ; height of aperture, 0.38 inch ; breadth of do., 0.2*7 inch. 



So far as I am at present informed, this is the first Devonian 

 species, beyond doubt known to belong to this genus, that has yet 

 been described in this country; though it is certainly represented 

 in rocks of that age in Europe.' Our species is even more closely 

 allied to the typical Carboniferous forms of the genus, than it is 

 to the European Devonian species, such as Naticopsis subcostata 

 and N. margaritifera { = Natica subcostata and N. margaritifera, 

 d'Archic and de Verneuil). 



It is an interesting fact that the above-mentioned European 

 Devonian species represent both of the subgenera found in our 

 Coal-measures, the first belonging to the subgenus Trachydomia, 

 and the other to the typical section of the genus. 



Locality and position. Dublin, Franklin County, Ohio. Cor- 

 niferous group of the Devonian. 



NATICOPSIS (PLATYOSTOMA'?) ^QUISTKIATA, Meek. 

 Shell subglobose ; spire much depressed ; volutions four, in- 



' It is probable that several of the so-called Naticas of the European 

 Silurian rocks also belong to this genus, as may be the case with some of 

 the Americau Silurian species referred to Holopea, and other genera, from 

 •the study of mere casts. 



[June 6 



