Cope.] <^y [May 7, 



Second Contrib'ution'to the History of the Vertebrata of the Permian Forma- 

 tion of Texas. By E. D. Gope.^ 



{Bead before the Ameriean Philosophical Society, May 7, 1880.) 



Since my synopsis of this subject, published in May, 1878, the accession 

 of much new material had enabled me to make a number of important 

 additions to it. Notes which record some of these may be found in the 

 American NaturaKst for September and December, 1878, and for April 

 and May, 1880. The substance of these is included in the present essay. 



At the meeting of the National Academy of Sciences, held in New York, 

 in November, 1878, I pointed out that the scapular arch in the Pelycosatiria\ 

 consists of scapula, coracoid and epicoracoid, which 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. The tibiale and centrale of the tarsus 

 unite to form an astragalus which has no movement on the tibia. The 

 fibulare forms a calcaneum. The distal side of the astragalus presents 

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

 the cuboid. 



The structure of the scapular and pelvic arches is identical with that 

 already described by Owen as belonging to the Anomodontia. Several im- 

 portant characters distinguish this group from the Pelycosauria, but tbe 

 two together form an order which I have thought must, for the present at 

 least, be retained as distinct from tl^^e Rhynchocephalia. The characters 

 of this order, with its two sub-orders, are as follows : 



Theromorpha Cope. Scapular arch consisting at least of scapula, 

 coracoid and epicoracoid, which are closely united. Pelvic arch consisting 

 of the usual thi'ee elements, which are united throughout, closing the obtu- 

 rator foramen and acetabulum. Limbs with the phalanges as in the am- 

 bulatory types. Quadrate bone proximally united by suture with the 

 adjacent elements. No quadratojugal arch. 



Pelycosauria. Two or three sacral vertebrae ; centra notochordal ; inter- 

 centra usually present. Dentition full. 



Anomodontia. Four or five sacral vertebrjE ; centra not notochordal ; no 

 intercentra. Dentition very imperfect or wanting. 



The Rhynchocephalia have no distal ischio-pubic symphj'^sis, and appar- 

 ently no epicoracoid bone. They have an obturator foramen, and a quad- 

 ratojugal arch. 



The order Theromorpha approximates the Mammalia more closely than 

 any other division of Eeptilia. 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 

 sub-order Anomodontia to resemble that of the Mammals, and as I have 



* Abstract read before the National Academy of Sciences, April 20, 1880. 

 t See Proceed. Amer . Philos. See, 1878, p. 511 and 5-8. 



