1890.] NATURAL SCIENCES OF PHILADELPHIA. 163 



as tlie only reason for regarding Capuhis and Platyeeras as distinct 

 genera. Since the time that the American author first expressed this 

 opinion, a sufficient number of fossil examples have been found to 

 indicate clearly the real nature of these scars. A careful comparison 

 shows that they are not very different from those of typical Capuli, 

 though considerable variation is noticeable in the several forms and 

 even in shells of the same species. Extended comparisons do not con- 

 firm the recent statement of M. G^hlert ^ who thus remarks : " Sur les 

 monies internes des especes que nous publions, nous avons egalement 

 observe des impressions musculaires qui, tout en presentant certaines 

 analogies avec celles des Capulus recents montrent neanmoins des 

 caracteres distincts, suffisants pour justifier la creation du genre 

 paleozoique que avait ete prevu par Conrad, Phillips et Hall." 



As exhibited in C. infundibulum and some other species the 

 muscular scars consist of a transversely elliptic impression on each 

 side connected by a narrow band traversing the posterior side of the 

 shell. In adult examples the scars are situated about one-fourth 

 the distance from the apertural margin to the apex. In some ex- 

 cellent internal casts of Capulus protei (Qilhlert) from the lower 

 Devonic of Mayenne the muscular impressions are somewhat different 

 from those of congeneric species from America. The scar on the 

 right side is comparatively large, oval and well defined ; a narrow 

 sinuous band passes around the spire posteriorly and terminates on 

 the left side in an enlarged scar similar to, but much smaller than, 

 that on the right. In some specimens the linear band does not 

 appear to be perfectly continuous from one side to the other. 

 Capulus occidens (Walcott). 



Platyeeras occidens Walcott, 1884. Pala;. Eureka Dist., p. 254, pi. xxiv, figs. 

 9,9a. 



Capulus occidens Kf^yes, 1890. Am. Geol.,vol. V. 



Shell small, composed of about one and one-half volutions, the 

 last rapidly expanding ; spire minute ; body whorl oblique, rather 

 sharply rounded dorsally. Aperture large, irregularly triangular ; 

 labrum sharj), sinuous. Surface marked by numerous lines of growth ; 

 and apparently by a few small undefined longitudinal folds. 



Horizon and locality. Lower Carbonic: Eureka District, Nevada. 



This species appears to be more closely related to C. cyrtolites 

 Mch., from the Burlington limestone, than to any other congeneric 

 form of the INIississippi basin. The apex, however, is more closely 



1 Bui. Soc. geol. de France, (3), t. XI, p. 60-5. 



