700 REPORT OF NATIONAL MUSEUM, 1898. 



Eocene, and I subsequently obtained from the marine Eoceue of New 

 Jersey. Tiiese snakes were of large size, and display points of resem- 

 blance to the Boidie. Venomous snakes first appear in the Upper Mio- 

 cene. A'iperidii' were found by Lartet in France, and I have found 

 Crotalida' in the corresponding (Loup Fork) bed in Kansas. The evi- 

 dence from paleontology, then, is, so far, that the Peropoda appeared 

 earlier in time and the Solenoglypba later. This is in accordance witli 

 their systematic; relations. However, we have little to base an actual 

 phylogeny upon, from the paleontological evidence at present, and we 

 can only draw inferences from structural characters in their relation 

 to other groups of reptiles, and especially to the other orders of the 

 Squamata. 



It is probable that the Peropoda are the earliest and ancestral form 

 of the Serpentes, since they display characters in both the skeleton, 

 penial structure and viscera, which approach the Sauria. The Scole- 

 cophidia are allied to them, but can not be regarded as ancestral, but 

 rather as degenerate descendants, being connected with them by the 

 intervening group of the Tortricina. On the other hand, the ascending 

 series may be traced through the Colubroidea to the Solenoglypha. 

 Among the Colubroidea we may regard the Aglyphodonta as nearest 

 the Peropoda and the Opisthoglypha and Proteroglypha as side 

 branches. The latter lead to the Solenoglypha. AVe know of no 

 direct transitions between Opisthoglypha and Proteroglypha, but the 

 genera fhpiwdon Peters and Glyphodon Giinther, which have numerous 

 grooved teeth, furnished an ancestral type from which both could 

 have been derived. The Platycerca, some of which Bouleuger shows 

 have grooved teeth behind the fangs, may have been derived from the 

 same source. This phylogeny may be schematically represented as 

 follows : 



Solenoglypha 



ScoL EcoPHiD-tA Oris thogl ypha Pro terogl ypha 



Peropoda 



This diagram is closely similar to one published by Boulenger, with 

 whose conclusions 1 entirely agree.' 



Degeneracy has played an im])ortant part in the history of the Ser- 



' I hiul already stated the same conchisious in general in 1885 in the American 

 Naturalist. See Origin of the Fittest, 1887, j). 334. 



