NEW OR LITTLE KNOWN PERMIAN 

 VERTEBRATES. PARIOTICHUS. 1 



S. W. WILLISTON, 

 UNIVERSITY OF CHICAGO. 



The University of Chicago Expedition to the Permian of Texas 

 during the autumn of 1908 was very fortunate in rinding a skele- 

 ton of a small reptile enclosed in a nodular matrix, probably the 

 most complete of any specimen hitherto obtained from that forma- 

 tion. It is of especial interest since it gives, for the first time, a 

 natural skeleton of a cotylosaur with all its bones in anatomical 

 relations, scarcely a single one disturbed by extraneous force in 

 fossilization. The original nodule measured about six inches in its 

 greater, by five in its lesser diameter, and about two inches in 

 thickness. The nodule, as discovered, was split horizontally, the 

 thicker portion enclosing most of the skeleton lying upon its 

 back ; the thinner with portions of the bones partly enclosed in it, 

 and with the right front leg almost wholly so. One small piece 

 of the thicker side, and a yet smaller fragment of the thinner were 

 not recovered. The missing portions, however, are of minor im- 

 portance, and are in part supplemented by the two blocks. The 

 specimen was discovered on a gently sloping surface near the 

 Wichita River, north of Mabelle, by Mr. Paul Miller. 



The material of which the nodule is composed is a rather hard 

 argillaceous limestone, and has necessitated very patient labor on 

 the part of Mr. Miller, with awl and needle, in its preparation, 

 many of the bones being so small as to require the use of a magni- 

 fying glass. The skeleton, which measures nearly fifteen inches 

 in length, is closely coiled, the tip of the tail lying under the front 

 extremity of the skull. As exposed on the two blocks, the 

 hyoid bones are in place ; the pectoral girdle is very slightly dis- 

 placed, with both arms articulated ; the right arm is strongly 

 flexed at the elbow, with its outspread hand underlying the pos- 



1 " Cotylosauria," Journal of Geology, XVI., p. 139; Lysorophus, this journal, 

 XV., p. 229; Diplocanltis, Trans. Kansas Acad. Science (in press); Trematops, 

 Journal of Geology, XVII. (in press). 



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