SYSTEMATIC REVISION OF THE SUBORDER. 69 



Revised description of the family: The structure of this family is so aberrant 

 that it can not be contrasted directly with the other families. So far as the characters 

 listed under serial numbers in the other families may be used they are as follows : 



(i) Skull acuminate ; higher behind and becoming lower anteriorly. 



(2) Tooth line straight. 



(3) Neural spines (probably) low. 



Aberrant Pelycosaurs, littoral or estuarine in habit ; feeding upon mollusks and 

 crustaceans. Skull low, wide posteriorly and tapering to the anterior end. A large 

 superior temporal foramen and probably a smaller inferior one. Interparietal and 

 epiotic present. Incisor teeth approaching chisel-shape ; anterior maxillary teeth 

 broadly triangular and thin, with anterior and posterior cutting edges ; the posterior 

 maxillary teeth conical. Post-incisor teeth of the lower jaw all conical. On the 

 pterygoid and palatine and on the dentary large patches of stout crushing teeth. 



Revised description of the genus : The serial numbers can not be used in the 

 description of the genus. As there is but a single genus and species in the family the 

 description of the family is characteristic of the smaller groups. See the morpho- 

 logical description. 



Edapliosaurus posfonias Cope. 



Proc. Am. Phil. Soc, vol. xx, 1882, p. 448. Also Pal. Bull. 35. 

 Trans. Am. Phil. Soc, vol. xvii, 1892, p. 15, plate 11, figs. 5 and sar. 



Type: A nearly complete skull with the lower jaw of the left side and imperfect 

 axis. No. 4009 Am. Mus. Nat. Hist, Cope, coll.; from Texas. 



Original description : '' Description of tJie genus. — Temporal fossEe not over- 

 roofed; surfaces of cranial bones not sculptured. Mandibular and maxillary teeth 

 subequal. Posterior half of the mandibular ramus expanded inwards and supporting 

 numerous closely arranged teeth. Pterygoid, or perhaps an internal expansion of the 

 malar bones, supporting a dense body of teeth, corresponding to those of the lower 

 jaw. Teeth subconical. 



" The single species of this genus in my possession shows the folio wing"characters 

 of systematic importance. An arch extends from the parietal plane posteriorly and 

 downwards to the external base of the quadrate. The specimen is not yet in a con- 

 dition to show how much of this is parietal, and how much squamosal or opisthotic. 

 The proximal half of the posterior part of this arch is a distinct element, perhaps a 

 transverse process of the supraoccipital. A distinct element connects the basioc- 

 cipital on each side of the quadrate. The articular extremity of the latter has a deep 

 antero-posterior concave emargination. There is a flat bone extending from it ante- 

 riorly which is apparently pterygoid rather than quadrat o-jugal. The tooth-bearing 

 portion terminates opposite the middle of the basisphenoid. 



"The occipital condyle is undivided, and the basisphenoid presents the usual two 

 divaricating protuberances to the basioccipital. 



'■'•Description of the species: The facial plate of the os maxillare is subvertical, so 

 that the orbit is lateral. The latter is rather small. The malar bone is narrow, and 

 is continuous with the dentigerous bone of the palate. The latter has a thickened 

 posterior edge, which commences below the anterior part of the orbit, and extends 

 posteriorly to the middle of the basisphenoid. Thence the border turns forwards. Its 

 anterior edge is below the anterior border of the orbit, and the general form is a longi- 



