38 PROCEEDmGS OF THE NATIONAL MUSEUM. vol.37. 



tion of Como Bluflf, and the bed containing the fossils discussed in 

 this paper is described as follows : " 



In the Como Bluff, this layer [No. 24 of his section] has sandwiched into it 

 a 4-foot bed of sandstone (24b). The sandstone is of interest as marking the 

 horizon at which the few Jurassic mammals were found. The mammal layer 

 is the G inches of clay underlying this sandstone. Most of the American Juras- 

 sic mammal remains thus far found have come from one quarry, worked most 

 successfully by Marsh and later by the American Museum. This pocket seems 

 to be exhausted. 



The mammal layer, as measured by Loomis, is 80 feet below the 

 overlying Dakota, and 22 feet below the level where the American 

 Mnseimi parties collected skeletons of Brontosaurus and Diplodociis. 



While the mammal remains are distinctive of this layer, it is evi- 

 dent that the reptilian forms found associated with them are also 

 important as horizon indicators. 



NOTES ON THE FAUNA OF " QUARRY 9." 



Although large collections of fossil remains have been made from 

 the Jurassic of this country, the meagerness of our knowledge con- 

 cerning the stratigraphic succession of the forms found has often 

 been a subject of comment. That as our knowledge of the fauna 

 grows it will be found to be sufficiently diversified to separate the 

 formation into well-defined faunal zones appears quite certain, and 

 any evidence obtainable toward that end is most important. 



It is with that idea in mind that the following list of fossils from 

 this one layer in Quarry 9 has been compiled : 



List of type specimens from Quarry 9, Como Bluff, Alhdny doKnty. Wyoniiny. 



MaTmnals. — Allodon fortis Marsh. 

 laiiceps Marsh. 

 Astlienodon segnis Marsh. 

 Ctenacodon nmitis Marsh. 

 potens Marsh. 

 serratus Marsh. 

 Diplocynodon victor Marsh. 

 Doeodon striatus Marsh. 

 Dfyolestes arcuatus Marsh. 

 gracilis Marsh. 

 ohtusus Marsh. 

 priscus Marsh. 

 * vorax Marsh. 

 * Ennacodon affinis (Marsh.) 

 * crassus (Marsh.) 



"Bull. Amer. Mus. Nat. Hist., vol. 14, 1901, p. 194. 

 * Those marked with an asterisk indicate type-specimens in the paleonto- 

 logical collections of the U. S. National Museum. All others, unless otherwise 

 designated, are now preserved iu the Yale Museum. 



