Williston.] Mosasaurs. , 97 



to be a distinct element, not found in either Ophidia or Lacer- 

 tilia, the claims of the new order to existence are maintained. 

 In either case it is clear that the ophidian suspensorium is not 

 the squamosal bone." 



Unfortunately in these characters given by Cope there are 

 several errors. There is no distinct element connecting the 

 "squamosal" (prosquamosal) with the parietal bone above the 

 opisthotic. There is the same kind of a sternum present as in 

 the Lacertilia. The characters then left are the decurvature of 

 the parietal bone, the absence of true roots to the teeth, and the 

 absence of a sacrum. The last character is also incorrect, since 

 in some of the forms, at least, there are as distinct articular 

 condylar surfaces as in the Lacertilia. To the decurvature 

 of the parietal bone no great importance can be attached. The 

 absence of a sacrum and the natatory character of the limbs 

 are really the most important of all the characters adduced, 

 and, I believe, certainly entitle the Mosasaurs to an independ- 

 ent group among the Lacertilia. Among the last to criticize 

 the classification of Professor Cope is Baur/ 6 who reviewed the 

 whole history of the controversy, described and figured the 

 bones of the skull in an excellent way, and gave the following 



classification : 



PLATY^OTA. 



Superfamily Varanoidea. 



Families V'aranidce. 



Mosasa uridce. 



Superfamily Helotlermatoidea. 



Family Melodermatidae. 



11 1 see no difficulty in assuming that the Mosasaurs developed 

 from unguiculate Lacertilia, which were very close to the Var- 

 anidse. To express this affinity, I placed the Varanidse and 

 Mosasauridee in a superfamily, the Varanoidea. By this I 

 wanted to say that the Mosasauridse cannot be separated from 

 the true Lacertilia, to which the Varanoidea belong ; in other 

 words, that they cannot be placed as a suborder of the Squa- 

 mata, but have to be placed among the suborder Lacertilia. In 

 this opinion I have nothing to change." 



46. Science, Nov. 7, 1890. and Journ. of Morph., VII, p. 1, 1892. 



