A NEW EHYNCHOCEPHALIAN EEPTILE FROM THE 

 JURASSIC OF WYOMING, WITH NOTES ON THE FAUNA 

 OF " QUARRY 9." 



By Charles W. Gilmore, 

 Custodian of Fossil Reptiles, U. S. National Museum. 



Tlie specimens upon Avliich the present paper is based were col- 

 lected by parties of the U. S. Geological Survey, working under the 

 direction of the late Prof. O. C. Marsh. Although fragmentary, sev- 

 eral of the forms discussed have not hitherto been recognized in the 

 Morrison fauna, and are of additional interest from the fact that they 

 were found in association with the mammal remains from these beds. 



All of the specimens considered in this article are from " Quarry 

 9," Como Bluff, Albany County, Wyoming, and are now preserved in 

 the vertebrate paleontological collections of the U. S. National 

 Museum. 



OPISTHIAS, ne>A^ genus. 



The characters of this genus are included in the description that 

 follows of O pisthias varus^ the type-species. 



OPISTHIAS RARUS, new species. 

 Plate 11. 



Holotyjye. — The nearly complete left dentary with teeth. Cat. No. 

 2860, U.S.N.M. 



Parat^ype. — A second dentary from the left side of a somewhat 



smaller and apparently younger individual. Cat. No. 2858, U.S.N.M. 



In the collection there are parts of seven other dentaries pertaining 



I to this form, but the description to follow is based upon the two 



: specimens mentioned above. 



Description. — The left dentary of the holotype measures 34.5 mm. 



i in length, and appears to be complete with the exception of a small 



I part of the coronoid process. Although somewhat smaller in size, 



its great resemblance to the dentary of the living Sphenodon is most 



striking. 



Proceedings U. S. National Museum, Vol. 37— No. 1698. 



35 



