﻿BOYSEN RESERVOIR VERTEBRATE FOSSILS WHITE 187 



Horizon and locality. — Lower Eocene, Lost Cabin, NEi/^SW^/i sec. 

 T), T. 4 N., R. 6 E., of Wind River meridian ; White Hill, south side of 

 Cottonwood (Dry Muddy) Creek, 11 miles north-northwest (air line) 

 of Shoshoni, Fremont County, Wyo. 



Diagnoses. — A medium-sized species; interorbital breadth 33 per- 

 cent less than in G. hillsi Gilmore; interorbital area with 5 regular 

 alternating rows of bony scutes, supraorbital and median rows larger 



Figure 75. — Glyptosaurus donohoei, new species, type, U.S.N.M. No. 18316; squamatlon of 



dorsal surface of skull, X 1. ^£1 



than second and fourth rows; scutes raised into a boss as in rugosus 

 and nodosus; vertical diameter of orbit equal to interorbital breadth ; 

 scutes of the temporal region less regular in outline and about twice 

 the diameter of those of the interorbital area. 



Discussion. — This specimen, in conjunction with a braincase from 

 Pipestone Springs (U.S.N.M. No. 13805), permits a few additions to 

 Gilmore's (1928, 1938) discussions of the genus. 



The various elements that make up the braincase are securely fused, 

 as in Peltosaurus. The form.er location of some of the sutures can be 

 made out by lines of roughened bone. The condyle is elongate-oval in 

 outline, twice as broad as deep. The tubera basioccipitalia project 

 ventrolaterally from the basicranial axis and are expanded anteriorly 

 and posteriorly at their bases as though reinforced by flying but- 

 tresses. These expansions are thickened along their edges so that the 



