THE OSTEOLOGY OF SOME AMERICAN PERMIAN 

 VERTEBRATES^ 



S. W. WILLISTON 



Universit}^ of Chicago 



ARAEOSCELIS 



A few days before the close of the field trip of the University 

 of Chicago paleontological expedition of 1909, Mr. C. L. Baker, a 

 member of the party, discovered in a ravine near the west line of 

 Craddock's Ranch, near Seymour, Texas, a large lot of loose bones 

 lying on the surface. The spot where they lay was within a 

 hundred yards of the road which probably every collector in the 

 Texas Permian region had traveled many times, but had neglected 

 to investigate, because of its unpromising appearance. The bones 

 lay strewn over a considerable area, and included numerous forms, 

 a list of which, so far as they have been determined, I have given 

 in my American Permian Vertebrates. About a bushel of bones 

 and fragments of bones were collected from the surface at this time, 

 including some of the forms under discussion. Early the next 

 season Mr. Paul C. Miller extensively excavated the bone-bed 

 with most interesting and valuable results. At one end of the 

 deposit, a little distance from other bones, though on the same 

 level, he discovered a "nest" of small bones. Occurring in the 

 moist clay and isolated, the bones were first disclosed by the plow, 

 which naturally had a rather disastrous effect upon them, small and 

 dehcate as they are. As soon as the deposit was recognized, the 

 pieces of clay containing the loose bones, and the various nodules 

 in which others were inclosed were carefully collected. The closely 

 associated bones of the skeletons were more or less cemented 

 together by a hard-clay nodular matrix, which has been removed, 

 with difficulty, the more so because much of the preparation had 

 necessarily to be done under a dissecting microscope. Many of 

 the bones protruded freely from the nodules into the soft clay; 



' Contribiitiou from the Walker Museum, Vol. I, No. 8. 



364 



