NATURAL SCIENCES OF PHILADELPHIA. 209 



Ceratohyals, first pair connate. 



No postoibital and supertemporal bones. 



Urodela. 



Usual cranial bones present, but pterygoids reduced or wanting. 

 No '' postorbital or supertemporal bones." 

 Caudal vertebrte and frontal bones distinct. 

 Ethmoid a vertical plate on each side. 

 Mandible dentigerous, teeth pleurodont. 



Inferior pelvic elements horizontal, in contact, no osseous pubis ; ilium sus- 

 pended to a sacral rib. 



(Mostly no quadratojugal.) 



Gymnophidia. 



Usual cranial bones present and distinct, including frontals and pterygoids. 



Caudal vertebrae distinct. 



No " postorbital or supertemporal bones.''* 



Ethmoid an annulus surrounding cerebral lobes. 



Mandible dentigerous ; teeth anchylosed by their bases. f 



(A quadratojugal.) 



Stegocephali. 



Usual cranial elements distinct, including froti'tals and pterygoids, and add- 

 ing " postorbitals and supertemporals." 

 Caudal vertebrae ? 

 Ethmoid normal. 

 Inferior pelvic elements distinct. 



Mandible dentigerous; teeth with anchylosed bases, or 

 (A quadrato-jugal.) 



Andra. 



Frontal and parietal confluent, nasals wanting or rudimental ; other cranial 

 bones present. 



Postorbital, supratemporal and usually nasals wanting. 



Ethmoid an annulus (usually complete above) surrounding cerebral lobes. 



Caudal vertebra- represented by an elongate compound style. 



Inferior elements of the pelvis consolidated into a single vertical mass ; ilium 

 attached immediately to sacral vertebra. 



Quadratojugal. 



STEGOCEPHALI. 



Xenorhachia. 

 The vertebral centra not ossified ; ? the dentition pleurodont ; teeth simple; 

 ? no branchial hyal bones. ? Occipital condyles. 



c u 1 a t u s than the emargination at the base of the root occupied by the growing crown of 

 the successional tootli,as in other Batrachia. If the structure described by Dr. Gray exists, 

 it is in a species as yet unexamined by American zoologists. Professor Wiuchell, of Ann 

 Arbor, confirms my observation. 



In my Synopsis of higher groups of Batrachia (Journ. Acad Nat. Sci. 1866), I stated that 

 Amphiuma possesses minute scales. Gray, in 1850 (Catalogue Brit. Mus.), makes the same 

 statement, which Dumeril (1863. Catal. Mus. Paris) contradicts. I nmst accord witli Prof. 

 Dumenl, since a subsequent examination has convinced me that they do not exist. The 

 specimen in which the appearance of scalesi was presented was mislaid at the time of 

 writing, and I find it was due to numerous free portions of the true derm, which are con- 

 tinuous with the attached portions. 



* When the temporal fossa is overarched it is by expansion of the maxillary and quadrato- 

 jugal. (Stannius says "squama temporalis.") 



fThe teetli of Ctecilia are compressed with a trenchant posterior edge, which is crenate, 

 after the manner of Megalosaurus, Careharias, etc. Thus to the numerous genera of 

 Saurians and Selachians possessing this character, must be added a Batrachian. 



1868.] 



