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THE AMERICAN NATURALIST [Vol. XLIII 



epiotics present, supraoecipital unpaired, condyle unossified, 

 branchial apparatus will chrtlopcd, vertebral column slender, 

 limbs apparently absent, ribs long, somewhat eurved and flat, 

 neurocentral. Williston concludes: 



" The only aberrant character to distinguish Lysorophus from the 

 Urodela is the long and rather broad ribs, unknown among these 

 modern animals or their possible ancestors, the Branchiosauria. It is, 

 however, very evident that the earliest ancestors of both these groups 

 must have long ribs, and their persistence in Lysorophus would be 

 nothing remarkable.'' 



But why need we conclude that the early ancestors of the 

 Amphibia must have had long ribs.' There is no geological 

 evidence of such, and the oldest known branehiosaurian. Micrcr- 

 pclon caudatinn Moodie from the middle IVnnsylvanian cer- 

 tainly possesses very short ribs. The animals associated in the 

 Carboniferous with the Branchiosauria, as a rule, possess long 

 ribs, but do we need to infer that the Branchiosauria and the 

 Microsauria bad the same ancestry? 



In all the long stretch of geological time there has never 

 existed a branehiosaurian nor a true urodele which had long 

 ribs, and so far, aside from the frogs found in the Tertiary, 

 these are the only true amphibians known in the fossil state. 

 It is exceedingly incongruous to class the Microsauria and 

 Branchiosauria in the same order Stegocephala. Their organ- 

 ization is totally different. To be sure, the long ribs in Lyso- 

 rophus might have developed secondarily as W illiston suggests, 

 but why do we need to assume even this when among the mod- 

 ern Gymnophiona we find long ribs and every other character 

 which is present in the Lysorophus? It is also possible that 

 the Gymnophiona are true Caudata, in which case there would 

 be no distinction and it may be that Lysorophus will be of 

 great assistance in bridging over this gap between the Caudata 

 and the Gymnophiona. 



Certain it is that the form is a most interesting discovery and 

 one of the most important in the phylogeny of the extinct 

 Amphibia in many years. I quote herewith from a letter to 

 Dr. Williston from Dr. Broom which the former was so kind 

 as to send me during the course of our correspondence on the 

 subject : 



^ " The skull (of Lysorophus) is to my mind undoubtedly Urodele and 

 singularly like that of Amphiuma which I believe to be the nearest 

 living ally. I am convinced that it is not a Gymnophionid ..." 



