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VOL. S:^, 



inclined to regard this fenestra as pathologic. A second specimen, 

 consisting of the lower jaw associated with the greater part of the 

 skeleton from Meyers Creek, was also described by Wiman. This 

 material is in the University of Upsala, Sweden. 



CHASMOSAURUS species 



A supraorbital horn-core (U.S.N.M. no. 12018), collected by N. H. 

 Boss in the Kirtland formation, 5 miles west of Brimhall's Store, 

 San Juan County, N. Mex., in 1929, is provisionally identified as 

 pertaining to the genus Chasmosaurus. This identification rests 

 on its close resemblance in form and size to the horn-cores of a skull 

 of C. helli^ described and figured by Lambe (1915). I am fully 

 aware of the uncertainty of an identification based on such meager 

 evidence, but with our present knowledge of the ceratopsian Din- 

 osauria, the onh^ other possibility is that this specimen might per- 



FiGURE G. — Supraorbital horn-core of a chasmosaurid dinosaur, U.S.N.M. no. 12018 ; 

 a, Lateral view ; b, posterior view. A little less tlian one-third natural size. 



tain to Centrosawrus^ although in none of the skulls known to me 

 of this genus do the supraorbital horn-cores closely resemble, except 

 in size, the one before me. In either event the presence of a hitherto 

 unrecognized ceratopsian genus in the Kirtland fauna is indicated. 

 This horn-core is short, with a bluntly pointed tip and slightly 

 recurved. Broadly oval in cross section near the base with the 

 greatest diameter anteroposteriorly, its broad ventral surface is 

 hollowed and forms the upper boundary of the orbit. The surface 

 of the horn is channeled by the usual series of ramifying canals. It 

 is illustrated in figure 6. 



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