EXTmCT BATRACHIA. 381 



Mr. Miall* finds that Urocordylus, Huxl., possesses ribs like this genus 

 and hence suspects the identity of the two. The "oat-shaped scales" 

 composing the ventral armature of Urocordylus, however, constitute an 

 important distinctive feature. These are only found in two Ohioan 

 genera, viz., Sauropleura and Colosteus. 



Before I was fully acquainted with the structure in this genus, I re- 

 ferred some of the species to Sauropleura, which is quite distinct. 



I am acquainted with one species from more or less completely pre- 

 served skeletons, with portions or wholes of crania, and another species 

 from cranial specimens alone. They may be distinguished as follows : 



I. Vertebra elongate ; fan-like caudal processes narrowed. Size large ; 

 mandibular teeth of unequal lengths, with the apices turned backward; 

 0. remex. 



II. Species only known from cranial bones with teeth. Teeth equal, 

 erect, with acute conic apices, eleven in 005 m.; 0. rectidens. 



Oestocephalus remex, Cope. 



Sauropleura remex, Cope; Proceed, Acad. Nat. Sci., 1868, p. 217. 

 Jb.; Proceed. Amer. Philos. Soc, 1871, p. 41. 



Oestocephalus amphiurninus, Cope; Proceed. Acad. Nat. Sci., Philada., 1868, 218; Trans- 

 actions Amer. Philos. Soc, XIV., p. 17. 



This species is represented by nine specimens, generally with reverses, 

 and three or more others are probaby referable to it. Two specimens 

 display crania, and one, caudal vertebrae complete, with hind foot ; 

 another consists of part of the caudal series, while most of the others 

 are from the dorsal region. An instructive specimen represents the 

 posterior portion of the abdomen, with basal region of the tail, with its 

 fans, with its pelvic and limb bones. 



They indicate an animal of the average size of the AmpMuma means. 



The extremities of the vertebrse are deeply concave, but the centra 

 are so long as to prevent the concavities entering more than one-fifth of 

 the latter, each. The diapophyses are behind the middle, and are broad, 

 curved backwards, and acuminate as in Amphiuma. The centra have a 

 prominent median line below, with a longitudinal concavity on each 

 side. Five of them a little exceed an inch in length. Neural spines 

 moderate. The humerus is longer than the coracoid, and is considerably 



* Report on the Labyrinthodontia of the British Coal Fields ; Proceed. Brit. Ass. 

 Adv. Science, 1873. 



