122 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [YolV. 



Myalina sp. ? 

 Myacites sp. ? 

 Neritina sp. ? 

 Undetermined ConcMfers and Gasteropods. 



I believe tlie only instance in wliicli P. asteriseus has been found asso- 

 ciated with Triassic forms is the one mentioned in the Eeports of the 

 Fortieth Parallel Survey,* in which it is stated that it was found associ- 

 ated with what are regarded as unmistakable Alpine Trias fossils, and a 

 Spirifera, a palaeozoic type. Mr. Emmons says :t " It should be stated also 

 that these disks of Fentacrinus found in the Dun Glen limestone vary 

 somewhat from the type-specimens, and are all of larger size, reaching 

 one-fourth of an inch in diameter, while those of Jurassic age scarcely 

 reach one-fifth of an inch. Professor Whitfield suggests that the Dun 

 Glen variety may iiossibly be a new species." 



Eumicrotis curta was not found associated with Fentacrinus anywhere 

 in our district, but at several localities where the section was obscure it 

 • was found with 



Aiiiculopecten idaJioensis, 

 Lingula hrevirostris, 

 Myalina sp. ? , 

 Myacites sp."?, and 

 several undetermined species of Aviculopecten. 



The beds from which they were collected were above the "Eed Beds," 



but I was unable to determine their relation to the "Pentacrinus Beds." 



In other areas, Eumicrotis curta has been found associated with species 



of Jurassic aspect. In the areas surveyed by the Fortieth Parallel 



Survey, it occurs with 



BelemniteSj 

 Gryphcea. 

 Terehratula augusta Hall & Whitfield, | as Dr. White remarks, has 

 been considered by the authors as a Jurassic species. 



The Cephalopods (from l^o. 2 of the section described) by Professor 

 White are, according to his identifications, unquestionably Triassic ac- 

 cording to European standards, resembling certain Cephalopods of the 

 Muschelkalk of Europe. 



The only other Cephalopods from our Western Trias are those obtained 

 by the Fortieth Parallel Survey from the Star Peak Group, which have 

 been considered the faunal equivalents of the St. Cassian and Hallstadt 

 beds of the Austrian Alps. The Star Peak Group is referred by King 

 to the Upper Trias, and is supposed to correspond to the Upper Eed Beds 

 of the Eastern Seas (Boclcy Mountain Region, &c.). If this be so, we 

 may perhaps consider the "Meekoceras Beds" of the section as the 



* Descriptive Geology, vol, ii, p. 711. Systematic Geology, vol. i, pp. 279, 280. 



t Descriptive Geology, vol. ii, p. 711. 



t Report U. S. Geol. Expl. 40tli Parallel, Systematic Geology, vol. i, p. 292. 



