No. 446.] RECLASSIFICATION OF THE REP TILL I. 



sauriis, Mystriosuchiis) forms, analogous in their habits to t 

 modern Crocodilia. 



The Parasuchia are found by McGregor to represent ; 

 undoubted modification of the rhynchocephaloid or diaptosauri; 

 type. 



III. Order Ichthyosauria Blainville. 



The ichthyosaurs are also distinctively Diapsida, both 

 shoulder girdle and in basicranial structure. The latero-te 

 poral fenestra, however, is closed, perhaps secondarily. 1" 

 posterior position of the nares and the elongation of the sno 

 in front, is analogous to that in the Parasuchia and may 

 indicative of divergence from a common stem. 



The most primitive form, Mixosaurus affords a transition 

 the ambulatory limb type of the Diaptosauria. None of th 

 known orders of Diaptosauria, however, can as yet be consider 

 ancestral to the ichthyosaurs. 



IV. Order Crocodilia Wagler. 



We must exclude from the Crocodilia the Parasuchia 

 Huxley and embrace only the Mesosuchia and luisuchia 

 Huxley with the addition of the typical marine forms, t 

 Thalattosuchia, recently monographed by Fraas. 



V. Superorder Dinosalria Owen. 



It is a mistake to raise this group to the rank of 

 as has been done by some authors, because its thret 

 divisions certainly lead back to a common stem f 

 Permian which was not dissimilar to the type repi 

 the Protorosauria. 



The ordinal nomenclature still requires further 

 present I am disposed to place the carnivorous fo 

 order Theropoda Marsh, including two suborders, 

 losauria for the large types with so 



glas^ 



