392 5. W. WILLISTON 



to these, some poorly known forms that have long been classed 

 with the rhynchocephalian reptiles, under the assumption that 

 any primitive reptile in which the temporal region was unknown 

 probably was allied to Sphenodon, show such possible or probable 

 resemblances to Araeoscelis as to merit consideration. 



Squamata. — I have no hesitation in saying that the skull and 

 skeleton of Araeoscelis present distinctively primitive characters 

 of the Squamata, to such an extent indeed that I believe the genus 

 has a definite phylogenetic relationship with the order. In fact, 

 as far as the skull is concerned, all that seems necessary to convert 

 Araeoscelis into a primitive lizard is the erosion of the lower part 

 of the squamosal bone until only a slender rod is left along the 

 under side of the postorbital, and the development of streptostyly 

 in the quadrate, which would necessarily ensue with the loss of 

 the support of the squamosal. The quadrate is supported quite 

 as in the lizards by the tabulare and paroccipital, in conjunction 

 with the squamosal. The quadrate itself retains some of its primi- 

 tive characters in its moderately expanded upper end, which, how- 

 ever, is much less in extent than in other known contemporary 

 reptiles. It is visible in part from the side, and fully so from behind. 

 The postorbital is peculiar and unlike that of other known reptiles 

 in that it takes no part in the formation of the posterior border of 

 the orbit. In conjunction with the postfrontal it is quite like that 

 of the mosasaurs and lizards in its extension backward nearly to 

 the tabulare. Among mosasaurs I have seen indications of a 

 sutural division of the "postfronto-orbital," and I have little 

 doubt that the bone is really composed of the two elements. If 

 it be really only a single bone, it must be the postorbital, not the 

 postfrontal. In the reduction of the lacrimal to a small or vestigial 

 bone we have another pronounced lacertilian character, never 

 before observed in the earliest reptiles. 



Unfortunately I have been unable to determine all the details 

 of the palate. Although teeth are not known on the vomers^ of 



' For some years I was inclined to accept the conclusions of Broom that the 

 so-called vomers of most reptiles were not homologous with the vomer of mammals, 

 which represented the parasphenoid; and to adopt the name he proposed for them, 

 prevomers. The more recent studies of Gaupp, Fuchs, Versluys, and Terry throw 

 grave doubt, to say the least, over these conclusions. I therefore return to the use 

 of the term "vomer." 



