UI^DOUBTED TERTIARY SPECIES. 193 



roUmncea, but It differs exti'emely in form from that type. I have therefore 

 proposed for its reception a new subgenus under the name Polyrhytis* 



I have seen but a single specimen of this shell, consisting of a well-defined 

 mould, from which a gutta-percha cast has been taken, and from this the 

 figures and description were prepared. The specific name is given in honor 

 of Clarence King, esq., the Geologist-in-charge of the Survey of the Fortieth 

 Parallel. 



Locality and position. — Cache Valley, Utah; Tertiary, probably of 



Miocene age. 



OERIPHASIID^. 



Genus GONIOBASIS, Lea. 

 GoNiOBASis SiMPSONi, Meek. 

 Plate 17, figs. 7,7 a, 7 b, 7 c, and 7 d. 



/ 



Melania Simpsoni, Meek (1860), Proceed. Acad. Nat. Sci. Philad., XII, 313. 

 Goniobasis ? Simpsoni, Meek (1866), in Conrad's Smithsonian Check-List, 12 ; and (1876) 



in Col. Simpson's Report Expl. across the Great Basin of Utah, 365, pi. v, figs. 



1 a to 1 e. 



Shell attaining nearly a medium size, elongate-conical ; spire gradually 

 tapering apparently to an acute apex, which is not eroded ; volutions eight 

 or nine, flattened or more or less convex, increasing gradually and regu- 

 larly in size ; last one rounded below ; suture generally linear, and some- 

 times presenting a very slightly banded appearance, or becoming deeper as 

 the volutions assume a more convex outline. Surface ornamented with 

 more or less distinct, regular little vertical, or slightly arched costae, which 

 are crossed by small, often obscure, revolving, raised lines, usually largest 

 and most widely separated on the lower half of the body- volution ; costse 

 sometimes assuming a very faintly nodose appearance around the middle 

 of the volutions. Aperture rhombic-subovate, and a little oblique, slightly 

 sinuous at the base of the columella ; outer lip somewhat sinuous above, 

 and moderately prominent below. 



Length of a mature specimen, 0.78 inch; breadth, about 0.30 inch; 



* This subgenus bears the same relations to Limnaia proper, that Costella, Dall, 

 bears to the topical forms of Physa. It was first proposed by the writer in the Palaiont. 

 Upper Mo., 532, 1876. 

 13 PR 



