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belong, I am satisfied, with the Theromorpha. The Pelycosauria, like 

 other primitive reptiles, have the ribs attached invariably to the inter- 

 central space and the diapophysis ; that is, they are double-headed 

 throughout, while the Cotylosauria, with like attachments, may have 

 the articulation continuous from head to tubercle. 



In the pectoral girdle about all the difference that Erythrosuchus 

 presents from the phytosaurs is a distinct supracoracoid foramen — 

 precisely the character that would be expected in the more primitive 

 form; and the pelvis, while agreeing in the main with the phytosaurs, 

 differs very materially from that of the pelycosaurs. The chief differ- 

 ences that the author finds allying the genus to the pelycosaurs, are, 

 as stated, found in the limbs: " Erythrosuchus kann, trotz der vielen 

 Ahnlichkeit uberhaupt, kein Parasuchien sein, da das Femur besonders 

 in der Bildung des Proximalendes mit den primitiven und alteren 

 Pelycosaurien und Cotylosaurien .... vollig iibereinstimmt. " Ad- 

 mitting this "complete agreement" of the proximal end of the femur 

 between Erythrosuchus and the Pelycosauria and Cotylosauria, can one 

 not conceive that the resemblances have been brought about by 

 adaptation to like conditions, that the characters are adaptive and not 

 genetic here, as so often elsewhere ? But I do not admit this complete 

 agreement. There is much variation in the femora of the cotylosaurs 

 and pelycosaurs, as witness those of Dimetrodon, Araeoscelis, Diadectes, 

 Seymouria, and Labidosaurus. The humerus of Erythrosuchus, although 

 it has a large lateral process and greatly expanded ends, differs materi- 

 ally from that of the pelycosaurs and cotylosaurs in the absence of the 

 entocondylar foramen. One does not refer the moles to a distinct 

 order of mammals because of the differences in the humeri from other 

 rodents. 



The skull structure of Erythrosuchus, with its upper temporal and 

 antorbital vacuities, is so much at variance with the theromorph rep- 

 tiles, that I can see no possible evidence of genetic relationships between 

 them. Unless Huene would make the Archosauria a part of the same 

 branch, from the root of the Pelycosauria, he attempts to prove too 

 much, for he would make the Pelycosimia a distinct branch or phylum 

 of the reptilia and entitled to more than ordinal distinction. He classes 

 the Pelycosauria with the single-arched reptiles and is correct in so 

 doing, but I confess I am not quite clear as to the real distinctions 

 between upper and lower temporal vacuities in such reptiles. Nor 

 does Huene seem to be either, as witness the following quotations: 



Op. cit. page 41, second paragraph: "Da bei Deuterosaurus das 



