306 OAltBONXFEEOUS FORMATIOKS AND FAUNAS OF COLORADO. 



from the Kinderhook species, En. <(ltirost7'is, being smaller, more finely striated, 

 and apparently without a sinus or strong median furrow therein. 



Lovaiifi/ and horhon. — San .Fuaii region (stations 2M81, 23S2); Ouray limestone. 



CAMAROTCECHIA Hall and Clarke, 1893. 

 Camarotckchia metallica White. 



1874. Rhynchonella metallica. White, U. S. Geog. Geol. Surv. \V. 100th Mer., Prehni. Rept. Invert. 



Fbss., p. 20. 

 Carboniferous (Coal Measures): Old Potosi mine, Lincoln County, Nev. 



1875. Rhynchonella metallica. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 129, ])1. 10, 



figs. lOrt-rf. (Whole volume published in 1877.) 

 Carboniferous: Old Potosi mine, Lincoln County, Nev. 

 1877. Rhynchonella pustulosa? Hall and AVhitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 257, 

 pi. 4, figs. 12-14. 

 Waverly group: Logan Canyon, Wasatch Range, Utah. 

 1899. Camarotcechia metallica. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 540, pi. 69, figs. 3a-3e. 

 Madison limestone: Yellowstone National Park. 



In the San Juan region (at station 2382) occurs a form which, though it is I'epre- 

 sented by scant}' and rather imperfect material, is referred with some confidence to 

 Camarotcechia 7netallica. At all events, with but little doubt it is the same form which 

 1 identified with that species in tlie Madison limestone of Yellowstone Park. I 

 believe, too, that the type specimen of O. metallica is not of Upper Carboniferous 

 age, as stated in the original description, but belongs really to the Madison fauna. 



Locality and horizon. — San Juan region (station 2382); Ouray limestone. 



PELECYPODA. 



CRENIPECTEN Hall, 1883. 



Crenipecten hallanus Walcott. 



1884. Crenvpecten hallanus. Walcott, U. S. Geol. Surv. Mon., vol. 8, p. 231, pi. 8, figs 7-'7c. 

 Lower Carboniferous: Eureka district, Nevada. 



At locality 2382 in the San Juan region were found two specimens, imperfect 

 internal and external casts, of a rather large pectinoid shell which probably belongs 

 to the species Crenipecten hallanus Walcott. The strife are rather coarse, much 

 more so, for instance, than in the related Or. unncheUi. Thej' are somewhat irregu- 

 larly alternating, and are crossed by numerous delicate, somewhat liexuous, imbri- 

 cating lamellose strife. 



Cr. hallanus was described from strata in the Eureka district, Nevada, which 

 I believe to be of Osage age, and so can not be far from the horizon at which the 

 material from Colorado was obtained. 



Locality and horizon. — San Juan region (station 2382); Ouray limestone. 



