Cretaceous Lizards and Rhynchocephalians. 205 



of the family Varanidas, agreed, so far as could be judged from 

 the figures published by Kornhuber, with Owen's Dolicho- 

 sauriis, and that the suborder Dolichosauria might prove to 

 be the ancestral group from which the Lacertilia, Pythono- 

 morpha, and Ophidia evolved. This opinion was founded on 

 the archaic condition of the hind limbs and the number of 

 cervical vertebra3 ; the presence of the zygosphenal articula- 

 tion of the vertebrae, present in all Ophidia and several 

 Lacertilia and Pythonomorpha, lent additional support to 

 this hypothesis. 



As 1 expected, my views have not had the approval of 

 Dr. Baur, who, in a lately published paper on the skull of 

 Mosasaurs (1), adheres to his previously expressed opinion 

 that the Varanidte, Mosasauridas, and Helodermatidee should 

 be grouped together as a suborder " Platynota." 



With regard to the structure of the foot, he denies any 

 considerable difference between Kornhuber's Hydrosaurus 

 lesinenstSj which I referred to the Dolichosauria, and a true 

 Varaiius. But unless he contests the correctness of Korn- 

 huber's restoration of the metatarsals and propodials, his 

 statement does not refute my interpretation ; the figures 

 which I have reproduced (after Marsh and Kornhuber) speak 

 for themselves. On the other hand, when he says that he 

 has " no hesitation to assume that unguiculated limbs can be 

 transformed into paddles with numerous phalanges," I entirely 

 agree with him, and do not know that I have ever expressed 

 any opinion to the contrary. 



His other argument is that there is no evidence for the 

 supposition that the number of cervical vertebrge after having 

 increased in the Dolichosauria can have become gradually 

 reduced again until the Rhiptoglossan number five was 

 reached. If my critic admits, as I believe he does, that the 

 Rhynchocephalia are descended from the Stegocephala, which 

 have fewer than eight cervical vertebra3, and that the Khipto- 

 glossa are only an ultra-specialized branch of the typical 

 Lacertilia, he cannot well argue against the probability of 

 such a process of increase followed again by a reduction. In 

 fact, if he will refer to one of his previous contributions to the 

 phylogeny of the Eeptilia, he will find that he has no diffi- 

 culty in assuming that the Chelonians, with eight cervicals, 

 may have been descended from Plesiosaurians with very 

 numerous cervicals, the latter having been, as he himself 

 admits, derived from short-necked forms. That he now holds 

 " All forms which show a greater or smaller number of 

 cervicals [to] have with very little doubt developed from forms 

 with eight cervicals " shows that his views have undergone a 



