Williston.] Mosasaurs. 215 



perience, I have learned that a missing part of a specimen 

 could never be found in the immediate vicinity. A distance of 

 a single foot without a bone always means that no more of the 

 skeleton may be found in extensive excavations. 



And yet, some disturbances of the bones took place after fall- 

 ing to the bottom ; vertebrae are dislocated and paddle bones al- 

 most always separated. The skull is always attached firmly to 

 the vertebral column. When one finds a cervical vertebra 

 joined to its mate, he may confidently expect that the head will 

 be uncovered by further excavation. 



Bones of the hind paddles are always much less common 

 than those of the front, and such bones in position are among 

 the greatest of rarities. 



The animals were covered completely by a scaly skin, the 

 scales in size and shape so closely resembling those of a large 

 monitor that a further description is unnecessary. But a single 

 specimen showing these scales is known, that of the Tylosaurus 

 which has furnished the best paddles of the genus yet known. 

 The specimen was discovered by Chancellor Snow many years 

 ago on Hackberry creek in Gove county, and the large slab 

 with the bones was safely transported to the museum. Plate 

 lxix is made from the electrotype originally used by Chancellor 

 Snow in the description of the skin. 01 In plate lxx is given a 

 reproduction from the photograph which was used in the pro- 

 duction of the wood engraving. The two together will convey 

 a most perfect idea of the skin. The impression, or rather the 

 carbonized scales themselves, are from the anterior part of the 

 body, from the region over or just back of the scapula. 



In plate lxxi is given a restoration of Clidastes velox as it is 

 believed it appeared in life, based upon all the evidences 

 given in the foregoing pages. It is not possible that the picture 

 can be very far from the real truth. Whether or not the ani- 

 mal had colorational markings, it is of course impossible to say, 

 but that its shape was nearly like what the artist has depicted 

 is fairly certain. Possibly the abdominal region was larger 

 than is shown, but I believe not. 



64. Transactions Kans. Acad. Sci., vi, 54. 



