OASTROPO1>\ 



ir rarln.iu- > 



i MI mat>'l like tlit> >l<>r-uiii, the dorsal .slopes strongly concave on the first ami 

 second \\horls nearly Hat m flu- la-t, without undulations except near the aperture 

 of the largest exsun !'-: transverse lines sweeping backward from the edge of the 

 umliilicu-. ^tnmger than the connecting lines, the diHerence between the two sets 

 increasing with age. 



The original description of the species is not entirely correct, Dr. Miller 

 daimiriK' tliat the surface "never presents a cancellated appearance," but he seems 

 to have doubted the correctness of his observations since he adds, "at least not on 

 any ^nM-mien observed." Out of more than twenty specimens belonging to the 

 cabinet of one of the authors several preserve the surface markings in a fairly 

 satisfactory manner. These show that on the inner volutions the surface is 

 minutely though distinctly cancellated. The short connecting lines are delicate, 

 and as growth proceeds they become relatively more so, a short exposure to the 

 weather sufficing in many cases to efface them entirely, when the specimen will 

 appear to have transverse stria; only. Generally, however, when the stronger 

 set of lines is preserved, more or less convincing traces of the other set also are 

 retained. 



Compared with (-. ornntus the present species is distinguished by its sharper 

 lateral carinie, flatter and more concave dorsal slopes, almost total absence of 

 surface undulations, and by the backward sweep of the lines of growth. From C. 

 retrorsus it differs in being practically without dorsal undulations, in having a less 

 prominent dorsal carina, and in the flattening of the dorsal slopes of the last 

 volution. So far as the two species mentioned are concerned, C. carinnlus is clearly 

 di-tim-t. hut we cannot say as much when we compare it with C. conradi, a species 

 named and figured by Hall (Inc. cit.), without a description, as one of the fossils of 

 the Hudson River or Mu<|uoketa shales of Wisconsin and Iowa. Hall's illustration 

 represents a small Cyriolites very similar to C. carinatus, and, as the geological 

 horizon is about the same for both, it i* not unlikely that the two names apply to 

 the same species. To establish this as a fact would in our opinion necessitate a 

 comparison with Hall's original type of C. conradi, and if that is no longer possible, 

 it would be well to drop the name entirely. 



Formation and locality. Not uncommon in \\.- I'tlca group a t Cincinnati, Ohio, and a nunibcrof 

 localities In the rlclnlty of that city. Th species occur, probably alno in the lower shah- m-ln- 



n.iti i rlud In Wisconsin and Iowa, In which caae it may U- loolml fur In soiitlnTO Mlonoota as w< 



