40 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [boll. 106. 



part of the series is unbroken. This horizon has yielded the following- 

 species of fossils: 



Gervillia proplenra. Corbnla nernatophora. 



Cardium paupercalum. Gyrodes depressa. 



Tapes cyprimeriformis ? Tnrritella micronema. 



Don ax oblonga. Pugnellus fusiformis. 



Tell in a? isonema. Fasciolaria? ntaliensis. 



Tellina modesta. Pyropsis ■ -. 



Mactra emmonsi. Prionotropishyatti? 



An at in a lineata? Plaeentieeras . 



On East Canon creek below Parley's park, about 12 miles southwest 

 of Coalville, there are Cretaceous outcrops in which few of the individ- 

 ual beds of the Coalville section can be recognized, but this sandstone 

 (No. 3) is present and easily recognized by its fossils, of which it has 

 yielded the following species: 



Trigonarca obliqna. . Mactra emmonsi. 

 Cardium panperciilum. •Pugnellus fusiformis. 



Tellina? isonema. Bacnlites gracilis f 



Tellina? subalata. Prionotropis. 



Mactra ntaliensis. 



This outcrop was mapped by the Fortieth Parallel Survey as very near 

 the boundary between the Cretaceous and the Tertiary, but it is at 

 least possible that the heavy bed of coarse conglomerate 275 feet above 

 it and in the same conformable series also belongs to the Cretaceous 

 and simply represents a greater local development of the conglomerate 

 No. 5 of the Coalville section. 



The lists of fossils just given clearly show that a single fauna ranges 

 from near the base of the section at least to the top of No. 3, through 

 over a thousand feet of strata. It is true that certain species seem to 

 be confined to particular strata, but other species, and among them 

 some of the most characteristic ones, such as Inoceramus hibiatux, range 

 through nearly the whole thickness and each zone is connected with 

 the others by interlocking species. The lists also show that certain of 

 these zones are represented in other sections already described. For 

 example, No. 1 contains about all of the species that were found in the 

 lower division of the Upper Kanab section and in the coal-bearing beds 

 near Cedar city and Kanarra, and these strata may be regarded as 

 equivalent. Again, the faunal lists from No. 3 and from the Pugnellus 

 sandstone in Huerfano park, Colorado, have so many species in com- 

 mon that there can be little doubt that these beds are very nearly con- 

 tempor an eou s d eposits. 



Up to this horizon the Coalville section very clearly belongs to the 

 Colorado formation l and apparently represents almost the whole of it 

 as developed elsewhere. In Colorado there is never more than 300 to 

 400 feet of the Niobrara beds above the horizon of the Pugnellus sand- 

 stone. Still it is well to remember that the Niobrara consists largely 



1 Tlie word " formation" is here used in a somewhat loose sense for want of a better term to desig 

 nate a series of strata containing a single £anna. 



