146 PROCEEDINGS OP THE ACADEMY OP 



of the whorls are less distinct, and the flattening of the upper side of the 

 whorls is not quite so broad. These, we think, probably belong to the species 

 under consideration, as they differ from any of those described by Prof. Hall 

 from that locality, resembling them in other respects, in having a smaller 

 umbilicus, more rapidly enlarging whorls, and a more elevated spire. 

 Locality and position. Waterloo, Monroe Co., Ills. St. Louis Limestone. 



Straparollus similis, var. planus. This form differs from the last in having 

 its spire completely flattened so as to be upon a level with the last turn, and 

 in having a slightly larger umbilicus ; while the angle on the under side of 

 the body whorl is a little farther out from the umbilical side. The flattened 

 space on the upper side of its whorls also differs in sloping inwards instead of 

 being horizontal ; and its suture seems to be more distinct. Notwithstand- 

 ing these differences, these forms agree so very nearly in size and other re- 

 spects, that we do not feel quite warranted in regarding them as distinct 

 species. Should it be thought necessary, however, to separate them specific- 

 ally, the form under consideration can take as a specific name that by which 

 we have designated it as a variety. 



It is an interesting fact that these two forms taken together, present an 

 exact miniature representation of the two varieties of S.pentangulatus (Sower- 

 by's sp.) The fact, however, that the shells under consideration present all 

 the appearance of mature growth, and never attain more than one-twentieth 

 the size of S. pentangulatus, while they have only two or three whorls less, is, 

 we think, sufficient reason for regarding them as distinct. 



Locality and position. Same as last. 



Genus ORTHONEMA, M. & W. 

 (Etym. CjO-9-oc, straight ; w/ut.*, thread.) 



Shell elongate, many whorled ; volutions ornamented with revolving carina;, 

 crossed by nearly straight lines of growth ; body whorl not produced below ; 

 aperture angular above, slightly effuse below ; peristome incomplete ; lip 

 simple, nearly straight ; axis imperforate. 



The shell upon which we propose 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 carina?, and the spaces between, without 

 making the slighest curve. In first indicating the typical species of this 

 genus, (Eunema Salteri, Proceed. Acad. Nat. Sci. Phila. Oct. I860,) we referred 

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

 satisfied us that it cannot properly be 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 whoils closely contiguous at all stages 

 of growth ; while its inner lip is less developed, and its columella is not pro- 

 vided with a ridge or angle as in the typical species of Eunema. 



From the genus Turritella, some species of which our shell resembles in 

 form and general appearance, it differs in its slightly effuse and less rounded 

 aperture, disconnected peristome, and straight outer lip. It is probably more 

 nearly allied to Loxonema, than to any of the groups we have mentioned, but 

 presents the well marked difference of being provided with distinct revolving 

 carinse, and a straight, instead of a sigmoid outer lip. It will probably in- 

 clude several species of Turritel/a-li'ke shells from the Coal Measures. 



Genus LOXONEMA, Phillips, 1841. 



Loxonema multicostata. Shell small, conical; spire moderately elevated ; 

 volutions abcut seven and a half, somewhat convex, increasing gradually in 



[June, 



