DESCRIPTIONS OF SPECIES. 47 1 



it belongs preciseh' to that species or to the closely- related B. harrodi I aui not able 

 to say. The species seems to be abundant in the Hermosa formation at station 2327. 

 Locality and /lorhim. — Sa.n Juan region (stations 2217, 2327); middle portion of 

 the Hermosa formation. Leadville district (station 2275); upper portion of the 

 Weber formation. Dolores River region. Sin1)ads Valley (station 2285); top of the 

 Heniiosa formation. 



PATELLOSTIUM Waagen. 1880. emend. Ulrich. 1897. 



Patellostium ourayense Gurley. 

 PI. X, figs. 10 to 10b. 



1<S84. Bellerophon oiirayensis. (iurley, New Carb. Foss., Bull. No. 2, p. 8. 



Upper Carboniferous: Duray, Colo. 

 1899. Patellostium orirayetue. Girty, U. S. Geol. Surv.. Nineteenth Ann. Rept., pt. 3, p. 589. 



It is unfortunate and somewhat sur]3rising that among the collections examined, 

 many of which must have come from the same horizon, and some from near the type 

 locality of Patell(Mmm onrayeiue. whicii Gurlev described without tigures in 1881, 

 no representative of that species has come to hand. Through the courtesj' of the 

 department of geology of Chicago University, however, I am enabled to figure the 

 typical specimen of that species which will be found represented by tigs. 10, 10a, 10b 

 of PI. X. The original description of Patellostium oi/nti/e/i»', quoted in full, is as 

 follows: 



"Shell medium size, subglobo.se, moderately expanding, slightly depre.ssed lat- 

 erally. Aperture reniform. arcuate. Umbilicus distinct, rather small. Lip con- 

 fonning to the general direction of the growth of the shell, thin, slightly reHexed at 

 the junction with the inner whorl. Lip divided into two lobes by a shallow mesial 

 sinus formed by the geitlo backward curve of the margin as it approaches the center 

 of the lip. 



'' Mesial band consisting of a sharply raised smooth ridge which is scarcely more 

 than a prominent well-developed revolving line. 



•'Surface marked by several sparsely arranged revolving striaj which become 

 very numerous and crowded close to the mesial band, there being seven striae within 

 a space of 2 millimeters on each side of the mesial band, while on the remaining por- 

 tion to the umbilicus there are only tive stria' occupying a .space of about 5 milli- 

 meters in width. The.se lines increa.se by iinplanation with the growth of the shell. 



"There arc numerous fijie, .sharply defined tran.sverse lines of growth which 

 curve gracefully Ijackward as they approach the cai'ina. These lines of growth are 

 equally as prominent as the revolving strife, and terminate a short distance from the 

 sharp, raised mesial band. The revolving strife and transvei'se lines of growth give 

 the surface a leather coarse imbricate appearance, although in crossing each other the 

 lines are uninterrupted. 



"This species has the general form of B. stevensanus McChesney, possessing 

 the laterally depressed sides and sharply raised mesial band seen in that form, but 

 differing very matei'ially in the ornamentation. 



