GASTROPODA. - ls7 



Ixjpbwplr* uulln.] 



The prominence of the peripheral bund varies considerably. As a rule it is the 

 most pronounced in specimens from the Richmond group and least in those obtained 

 from the "Upper Nashville" of Tennessee and the Ix>rraine of Kentucky and Ohio. 

 The apical angle also is variable though fairly constant in specimens from a given 

 lucalitv and hori/.on. The Ix>rraine variety is the widest, the Trimble county 

 Kentucky, ami Tennessee specimens the narrowest The latter look like our fig. 42 

 only not so angular. Fig. 40 is perhaps a fair average for the species. 



Cincinnati collectors formerly confounded casts of this species with Hormoioma 

 btllicinctn Hall sp., but we now know it as a totally distinct shell. Hormotoma has a 

 concave band and, as may be seen from our figures, differs in many other respects, 

 while L. boicdeni has the band of a Lophospira and in reality differs from such a 

 typical species of the genus as L. oioeni chiefly in the bight of the spire. 



Formation and locality." Upper Nashville" near lUrUsville and at other localities In Tennessee: 

 Lorraln.- tfnmpat numerous localities In Ohio, Indiana and Kentucky; Illchniond group at many localities 

 In the same state*, especially In the upper fifty feet In Kentucky. 



CbUMtfmu.-Prof. J. M. Safford; E. O. Ulrtch. 



ArousTiNA Billings. 



PLATE LXXI. riOB. 1 and !. 



auyutiina BILUMOA, 1805, Pal. FOM., vol. I, p. 234. 



Hight 80 to 120 mm., apical angle 33 to 40; whorl? eight or nine, perhaps 

 ten, yet casts of the interior, in which condition only the species has been observed 

 in Minnesota, rarely preserve more than the last four or five. Whorls (of casts) 

 strongly convex, obtusely angulated just below the middle, angular above, forming 

 a narrow horizontal space at the broad open suture. Aperture about as wide as 

 high, slightly drawn out and channelled at the lower angle. The lip is free all 

 around, on the upper side in contact with the penultimate whorl, on the inner side 

 with a broad fold which never quite closes the umbilical perforation. The latter is 

 represented in casts by a flattened spirally twisted core. Casts of the interior 

 preserve not even a trace of the surface markings, nor are they clearly indicated in 

 the molds of the exterior seen by us. As near as can be determined from the 

 material at hand, they consist, as described by billings, of obscure undulations 

 curving strongly backwards to the rounded peripheral band. The shell itself was 

 strong and thick, especially in its sutunil parts. 



This is one of the forms usually identified with Hall's Murchixnui'i major, but if 

 our views of that shell are correct, then this is most certainly <li.-tinct. while it 

 seems to be equally certain that it is the same as the Newfoundland species which 

 Billings has called Murchixuni>i nwjustina. Billing-, it i- 1 rue, considered the august inn 



