28 KANSAS UNIVERSITY QUARTERLY. 



The description, otherwise, shows no discrepancies of importance. 

 The chief difference given by the author is the size, and this character 

 we think our specimens show to be of little specific value. "It is a 

 question of some importance how far difference in size among the 

 Mosasauroids may be a test of difference in species. Among the 

 numerous remains of these animals which have been discovered I have 

 never yet observed any which presented any evidence relative to age. 

 * * * In this view of the case, some of the many described species of 

 Mosasauroids may have been founded on different sizes of the same."* 



The length of the cervical vertebrae in the specimen above de- 

 scribed is thirty-seven or thirty-eight millimeters. The cervical verte- 

 brae in two specimens referred to C. pitinilus have lengths respectively 

 of twenty-two and thirty millimeters. In the type speciriien of C. 

 velox they must have had a length of at least forty-two millimeters. 



It thus appears that, between the smallest specimen, which, in life, 

 could have hardly exceeded eight feet in length, our specimens, 

 indistinguishable anatomically, represent forms of ten and twelve feet, 

 while the type itself was about fifteen feet in length. 



Of the material originally referred to C pumilus, there are in the 

 collection five or more specimens, which, altogether, furnish nearly 

 every part of the skeleton. They present no tangible differences from 

 the skeleton of C- vclox described above. There can be, hence, little 

 or no doubt but that the name C. pumihis is a synonym. 



It is hardly possible to say with certainty that C. affiiiis Leidy is or 

 is not the same as C. velox, but, so far as the description goes, we can 

 find few differences. The type is of about the same size as the type 

 of C. velox, and the figures agree well with the bones of the skeleton 

 described. Although the description was not published till 1873, the 

 author makes no mention of the species of Marsh's. Leidy de- 

 scribes the back teeth as having the enamel strongly striated, with the 

 surface presenting evidences of subdivision into narrow planes. In 

 this respect, only, it disagrees with the specimen. 



Plioplatccarpiis Dollo is described by its author as having a sacrum 

 of two conjoined vertebrae, f by reason of which it is placed in a sep- 

 arate family from the rest of the PythonomorpJia. It may be pre- 

 sumptious to express a doubt of the genuineness of the sacrum, and 

 yet, save from the fact that the author found two specimens quite 

 alike, one might doubt it strongly. It is not very rare that two, or 

 even three vertebrae are found united from injury in these animals, 

 and Such would readily account for the consolidation as figured and 

 described by Dollo, except for the coincidence of the second speci- 



* Leidy, Rep. U. S. Geol. Surv. Havden, vol. i, p. 284. 

 fBull." Su. Mus. Roy. S. Hist. Nat.^'d. Belg. i, p. 8, 1882. 



