•174 CARBONIB'EBOUH FORMATIONS AND FAUNAS OK COLORADO. 



Locality (ind liar'non. — San .Iiian rcoiini (stiiUoiis ii204i, a221i, 23;:i7); upper 

 portion of tlic Ilcrnios;! t'orniation. Leach illc disirict (station 2275?); upper j)orti()n 

 of tli(" W(vl)(ir formation. 



I'ATKi.i.osTiuivr BKT.i.iiM Keyes. 



IS'iri. lirUfroiiliiiii hi-lhix. Keyi's. ^lif^f^ciuri (Icol, Surv., vol. -"i, p. 148, pi, rii\ tig. 7. (Dateof imprint 

 1894.) 

 Upper Coal Measuivs: Kansas Cit.v, Mn. 

 18!)H. PatpModiutn noddrontiitinii. (xirty (non (airlcy), 1'. 8. Geol. Snrv., Niiieteentli Ann. Rept., pt. 

 :?, p. WO. 

 Upper Ooal Measnres: Atoka quadrangle. 



The Hiatei-ia! representing this species is so very scanty, fragmentary, and poorly 

 preserved that I find myself unable to identify it with the accuracj'^ desirable. That 

 from the Hermosa formation (Rico quadrangle, Sandstone Mountain, station 2217), 

 though the surface ornamentation is partially obscured, is close to /-". hellwm, and 

 probably better material would sanction the identification. From the Rico formation 

 but two specimens have V)een obtained. One from station 2340 is practicallj' inde- 

 terminable, but probably is conspecific with the other. The specimen from station 

 2337 seems to be somewhat different from the form obtained from the Hermosa 

 formation. It shows a small area of surface in fairly good preservation, whose 

 ornamentation differs from that of P. helhtm. in having the transverse strife finer and 

 sharper and the revoh'ing striae finer and more nearly equal. It is possible, there- 

 fore, that the Patclloatiu.m which occurs in the Hermosa formation is not the same 

 as that from the Rico formation. 



On a former occasion I ventured to throw Patellostiurn helium Keyes into the 

 synonymy of P. nodocoHtatum, Gurley. basing the opinion upon Gurley's description 

 on one hand and on the other upon specimens from Rulo. Nebr. , thought to belong- 

 to P. helUmn. Through the courtesy of the department of geology of Chicago 

 University I have enjoyed the privilege of examining the types of Gurley's species 

 of BelleropJum, and now feel compelled to reverse the judgment expressed at that 

 time. In view of its intimate relations with several of Gurley's species, the small 

 figure and brief descrijjtion of Keyes afford an inadequate conception of P. helium. 

 Nevertheless the Rulo specimens are still believed to belong to that species. From 

 these P. ihodocostatwin differs in having the transverse striae somewhat stronger an d 

 the revolving strire finer. The latter, therefore, instead of being equal to the trans- 

 verse ones, as in /*. helium^ and merging with them at the intersection into indistinct 

 nodes, are in P. nodocnstatum considerably finer and cross the transverse ridges 

 without becoming confluont. They become, in fact, stronger and more prominent 

 on their crests. 



The ornamentation of P. UxtUifm'me is similar to that of P. nodocoiitatum , but 



