No. 446.] RECLASSIFICA TION OF THE REPTILIA. J 07 



rder Diaftosauri a Osborn. 



This SLiperordcr embraces the Rhyn- 

 chocephaHa of Gunther, the Pelycosauria 

 of Cope, which certainly represent dis- 

 tinct orders of reptiles, and the more or 

 less distinct orders or suborders Protoro- 

 sauria, Procolojihonia, T^roganosauria, 

 Choristodera, Gnathodontia, Rhynchoce- 

 phalia. They have appropriately been 

 termed ' rhynchocephaloid ' reptiles by 

 Broom. 



The common characters of these prim- 

 itive or stem Diapsida, are as follows : 

 cranium with two complete temporal 

 arches ; vertebrae typically amphicoelous 

 and often perforated by a notochordal 

 canal ; hypocentra frequently present 

 throughout vertebral column; 1 ibs on 

 all vertebrx from first ceivual to eighth 

 caudal inclusive, geneialh Mn-,lc uud 

 or incipiently two-headed ; laiK<- cdxlonn 

 nal nbs or pListion alwa). picscnt 

 coracoid and piocoracoid eail\ uniting 

 into a single bone; pubis and ischium 

 ventrally m continuous contact or sec- 

 ondarily fenestrated. 



The adaptive radiation of these mostl> 

 small sized animals into am1)u]atoiy. lit- 

 toral, amphibious, and fully ac|iuitR tN i^s, 

 together with specializations ot the skull 

 cind dentition foi a gieat \anct\ <)t tcul 

 mo habits has usultcd m i (hvu^ciu. 

 sufficiently protound ancl ancient^ tu 



iTrLsir assigned \he lank of ordcis 

 or suborders as follows . 



