A MOUNTED SKELETON OF PLATECARPUS 



S. W. WILLISTON 

 The University of Chicago 



In the summer of 1903, Professor E. B. Branson, then a student of 

 the University of Chicago, discovered, near the mouth of Hell Creek 

 in Logan County, Kansas, and collected with my aid, a remarkably 

 complete specimen of a species of Platecarpus, which I refer, with 

 little hesitation, to P. (Holosaurus) ahruptus Marsh. In its vicinity 

 another specimen almost identical with it in size and characters was 

 discovered by Mr. E. Ball of the same party. A brief reference to 

 some of the characters of the more complete of these two specimens 

 was given by me in this Journal for January, 1904 (p. 30), and, later, 

 Mr. S. R. Capps, under my advice, made a careful study of the hind 

 extremity, publishing his results in this Journal for May, 1907 (p. 350). 

 Since then both of these specimens have been thoroughly worked out 

 of the matrix by Mr. Paul Miller, and one of them has been mounted 

 as a wall specimen in the Walker Museum of the University of Chicago, 

 a photograph of which is given in the present communication. It 

 was first planned to mount the more perfect of the two specimens, 

 but the horizontal flattening of the skull rendered it less adaptable 

 for a plaque mount, and the specimen has been reserved for a free 

 skeletal mount at some later time. The less complete of the two has 

 therefore been placed upon the wall, its missing parts reproduced 

 by casts from the more perfect one; this specimen fortunately had its 

 skull bones preserved separately, in a macerated condition, with but 

 little or no distortion, permitting their articulation in a normal posi- 

 tion. The vertebral column was very complete and continuous to 

 about the seventieth vertebra, that is the forty-seventh of the tail. 

 The pectoral girdle, save the right humerus, and most of the hind 

 paddles and pelvic girdle were preserved, in large part, in their 

 natural relations; of the ribs many of the shorter ones were gone; 

 these, together with the distal portion of the tail, have been reproduced 

 from the other specimen, and the left humerus has been used instead 



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