14 



THE HISTORY OF THE PELYCOSAUEIA, WITH 



emy of Sciences, at its meeting in New York, on the Theromorphow Beptilia. " He stated 

 that he had determined that the scapular arch in the Pelycosauria consists of scapula, 

 coracoid and epicoracoid, winch form a continuum in the adult, in the same way as the 

 three elements of the pelvis in the same group form an os innominatum. He showed 

 that the tibiale and centrale of the tarsus unite to form an astragalus, which has no move- 

 ment Oil the tibia. The fibulare forms a calcaneum. The distal side of the astragalus 

 presents two facets, one of which receives a large part of the proximal extremity of the 

 cuboid. 



"The structure of the scapular and pelvic arches was slated to Ik; identical with that 

 already described by Owen as belonging to the Anomodoniia. Several important char- 

 acters distinguish this group from the Pelycosauria, but the two together form an order, 

 which Prof. Cope thought would have, for the present at least, to be retained as distinct 

 from the RhynchocephaKa. The characters of this order, with its two suborders, were 

 given as follows : 



" TheeoMOKPHA Cope. Scapular arch consisting at least of scapula, coracoid and 

 epicoracoid, which are closely united. Pelvic arch consisting of the usual three elements, 

 winch are united throughout, closing the obturator foramen [f. pubo-ischiaticum] and 

 acetabulum. Limbs with the phalanges as in the ambulatory types. Quadrate bone 

 proximally united by suture with the adjacent elements. No quadratojugal arch. 



" Pelycosauria. Two or three sacral vertebrae ; centra notochord a 1 ; intercentra usu- 

 ally present. Dentition full. 



" Anommlontia. Four or five sacral vertebras; centra, not notochordal ; no inter- 

 centra. Dentition very imperfect or wanting. 



"The Rhynchocephalia have no distal isehio-pubic symphysis, and apparently no 

 epicoracoid bone. They have an obturator foramen [foramen pubo-ischiaticum] and a 

 quadratojugal arch. 



"The order Theromorpha was regarded by Prof. Cope as approximating the Mamma- 

 lia more closely than any other division of Reptilia, and as probably the ancestral group 

 from which, the latter were; derived. This approximation is seen in the scapular arch 

 and humerus, which nearly resemble those of the Monotremata, especially Echidna; and 

 in the pelvic arch, which Owen has shown in the Anomodontia to resemble that of the 

 Mammals, and, as Prof. Cope pointed out, especially that, of Echidna. The tarsus is also 

 more mammalian than in any other division of reptiles. In the; genus Dimetrodon the 

 coracoid is smaller than the epicoracoid, as in Monotremes. Tin; pubis has the foramen 

 for the internal femoral artery." 



At the end of this note a new species of Dimetrodon is described under the name 

 of D. cruciger. "It is characterized by the enormous length of the neural spines of the 



