NO. 1353. TWO NFAV FOSSIL VERTEBRATES— LUCAS. 195 



center of the shaft, and the sharp definition and differentiation of the 

 radial and idnar articulation.s. While tlie deltoid ridge i.s prominent 

 in man}' Anomodonts, it is peculiar in the present species from the 

 fact that it seems to have started practically from the proximal end 

 and not from a little distance down the shaft, as it does in such a form 

 as (xomphog'nathus." 



The hunuM'us of Plaeerias otherwise bears a slight resemblance to 

 tiiat of Gomphognathus, ])ut is vastly larger, and indicates an animal 

 of much greater size and power. Among African Anomodonts the 

 humerus suggests most that of Cynodrakon, but here again it is much 

 more expanded proximally. A .large, elongate entepicondylar for- 

 amen was present, but the portion bounding the outer side of this is 

 missing and its position is not clearly indicated on the accompanying 

 plate. The articular face for the radius is large, round, and well 

 defined, and the olecrenal fossa is of good size; the proximal end of 

 the humerus was capped with cartilage, but the amount in the el))ow 

 joint must have been small. The indications are that Plaeerias was a 

 creature largeh", if not entirely, terrestrial in habit. 



The measurements of the humerus are as follows: Greatest length, 

 3i>S mm. (15f inches); estimated breadth across deltoid ridge, 200 

 mm. (71 inches); breadth of portion actually present, 170 mm. (6f 

 inches); breadth at lower end of deltoid ridge, l-ll: mm. (5^^ inches); 

 least diameter of shaft, OO mm. ('if inches); greatest distal breadth, 

 155 mm. (Gf inches). 



The large Cotylosaurians hitherto described from North America 

 are from the Permian, while the present specimen is from the Trias. 

 The animal represented is also larger than any of the Permian species, 

 and, in this respect, is on a par with Parlasaurus. The humerus, how- 

 ever, is quite different from that ascribed to Pariasaurus, and while 

 the discovery of animals of this genus in Russia indicates that the 

 group to which it belongs was widely distributed, it is evident that 

 the present specimen is not Parlasaurus. It is nevertheless quite 

 probable that Plaeerias belongs to some allied family, or possibly to 

 the same family. 



The beds from which the two species just described were obtained 

 also contained remains of the large Belodon, Jfetevodontasuehus ijanei 

 and of the dinosaur Paheoctonus. The same as.semblage of species 

 has recently been found l)y Mr. Newton 11. Brown near Lander. Fre- 

 mont County, Wyoming, which considerably extends the northerh" 

 limit of these Triasic beds. Aside from the interest attached to the 

 rinding of this new species is the more important fact, pointed out by 

 Dr. Fraas, that the gQ\\w>h Metoposauru^ is characteristic of the Keuper 

 of Europe, and that we have in these Triassic beds of Arizona, Utah, 

 and Wyoming the same combination of bclodont suul labyrinthodont 

 as in the Keuper. 



"Seeley, Trans. Roy. Soc, 1895, B, p. 29. 



