academy of sconces.] PUBLISHED RESULTS. 131 



them all in a single group, for the sole end of all taxonomy is phylogeny. Williston here defines 

 the two larger groups, the Cotylosauria and Theromorpha, discussing also the relationships of the 

 Old World Protorosauria and Proganosauria, and then describing the reptiles of the Lower 

 Permian of Europe. This is followed by a discussion of the position of the Microsauria and of 

 Lysoropbus, which he now believes to have no direct ancestral relationships with any modern 

 vertebrates, but to owe its resemblance to certain existing types to community of habit (see, 

 however, table facing p. 133). 



The genus Araeoscehs, originally described by Williston in 1910, is further discussed in 

 two papers in 1913. m,U4 His final conclusions as to its place in reptilian taxonomy are start- 

 ling, for he believes it to be the first known lizard, and that from the Lower Permian. Arse- 

 oscelis can not be placed in any known order of reptiles, unless it be admitted to the Squamata, 

 and he does not think that the differences from the Squamata will justify its ordinal separation 

 if we are to classify organisms phylogenetically. He says: "I would rather modify the 

 definition of the order Squamata to include the genus as a representative, doubtless with 

 Kadaliosaurus also, of a distinct suborder, the Arpeoscelidia." He believes that after he has 

 published the full details of Arseoscelis his readers will agree as to its phylogenetic association 

 with the Squamata as in the general acceptance of the genus Lysorophus as an ancestral urodele. 

 In "The Osteology of some American Permian Vertebrates," 1914, 12 - he gives this further 

 evidence in the form of a complete discussion of the osteology of Arseoscelis, the entire skeleton 

 of which is now known with the exception of the tail beyond the fourth vertebra. He again 

 compares the genus with certain foreign types, notably Protorosaurus, Kadaliosaurus, Paleo- 

 hatteria, the Proganosauria and Ichthyosauria, and thus concludes (p. 400) : 



I have urged that the resemblances of Arseoscelis to the Squamata would justify its inclusion in that order as a 

 suborder, under the name Araeoscelidia, coordinate with the Lacertilia and the Ophidia. And I believe that will be 

 its final disposition under some subordinal designation. But it seems to me that the relations with Protorosaurus and 

 Kadaliosaurus are too definite, too pronounced, to warrant their dissociation. I would therefore propose to unite these 

 three genera, together with, provisionally, Haptodus and Callibrachion, under the order Protorosauria of Seeley, and 

 place the order immediately before the Squamata in any serial classification of reptiles. 



This he brings out graphically in the table of 1917 (facing p. 133). 



A restoration of Arseoscelis is given, both skeletal and in the flesh, and the creature is 

 described as an extremely light and slender, terrestrial and arboreal reptile, with springing 

 powers, and possibly with a parachute development of the body membrane. Its length, when 

 adult, was about 2 feet. 



Another skull of the curious Casea adds to the information given concerning this reptile 

 in "American Permian Vertebrates." There is also a description of Arribasaurus, a new genus 

 based on Dimetrodon navajoicus Cope, and a discussion with figures of the primitive structure 

 of the mandible in reptiles and amphibians. 



A joint paper by Williston, Case, and Mehl appeared in 1913, 117 a large quarto memoir 

 on the Permocarboniferous vertebrates of New Mexico. This is divided into several chapters, 

 all but one of which are by Williston and Case. Chapter I is geological, a description of the 

 vertebrate-bearing beds of north-central New Mexico, whereas the others are all concerned 

 with vertebrate description, of which the most notable are the discussions of the skull of Aspi- 

 dosaurus, of a nearly complete skeleton of Diasparactus, of Ophiacodon, and of the pelycosaur 

 Edaphosaurus. 



Prof. Williston's book on "Water Reptiles of the Past and Present," 1914, 118 has been 

 repeatedly referred to, but its importance is such that it should be discussed in somewhat 

 greater detail. It summarizes in a most authoritative maimer our knowledge of the reptiles 

 which have become adapted to aquatic life, and also includes an important chapter on the 

 classification of reptiles, for, as he says, the classification of reptiles is still a matter of much 

 doubt and uncertainty, no two authors agreeing on the number of orders or the rank of many 

 forms. Many strange and unclassifiable types which have come to light in North America, 

 South Africa, and Europe, have thrown doubt on all previous classification schemes, and have 

 weakened our faith in all attempts to trace out the genealogies of the reptilian orders, and 



