AVD AVES OF NORTH AMERICA. 17 



ly on the median line. Limbs distinctly developed. Ribs long, well developed. Scales 

 none. 



In more detail, we have an elongate lanceolate head with little or no sculpture of the 

 external surface of the bones. The angles of the mandibles are much prolonged 

 backwards as in Apateon and frogs, and the well developed ribs commence but a short 

 distance behind the head. The vertebrae are slender, and furnished with well developed 

 diapophyses. 



The neural spines of dorsal vertebrae in O. remex are flattened and expanded in the 

 line of the vertebral column, and weakly grooved to their superior margin. Their char- 

 acter has not been observed in the other species. 



The neural and haemal spines of the caudal vertebrae are prolonged, and remarkably 

 sculptured by longitudinal grooves, which are most distinct towards their terminations. 

 They are much flattened to support an oar-like tail. 



Anterior limbs have been seen in two species, and posterior in one other. Though 

 they all probably possess two pairs of limbs, this point is not entirely established, leaving 

 the "homogeneity of this genus still somewhat uncertain. 



A pair of symmetrical bones whose impressions are seen posterior to the occipital bone 

 appear to be the coracoid, and one of them is followed by a second element, which is 

 probably the humerus. A third piece follows, which is ulna, or radius; the second bone 

 of the forearm is lost, but some impressions, which appear to be those of a digit, are 

 visible. 



The skin has been occupied by a great number of closely packed, curved, spine- 

 shaped scales. They have occupied the ventral integument, passing from the median line 

 of the belly outwards and posteriorly, having acute tips which may or not have penetrated 

 the skin on each side. No such tegumentary spines protected the dorsal region. 



The three sculptured dermothoracic plates common to so many of this order, have not 

 been seen in this genus. 



As compared with Sauropleura, this genus is more elongate and snake-like, and with 

 much weaker limbs; these characters are not sufficient to distinguish it alone, but as no 

 dilated neural spines nor similar abdominal armature are discoverable in the former, I 

 prefer to keep them separate for the present. 



OESTOCEPHALUS REMEX, Cope. 



Sauropleura remex, Cope. Proc. Ac. Nat. Sci., Plrilada., 18G8, p. 217. Oestocephalvs amphiumintts, Cope. 

 1. c. p. 218. 



Additional specimens received from Dr. Newberry enable me to combine the caudal 

 vertebra? described as above under the genus Sauropleura, with the remainder of the skel- 



AMEEI. PHILOSO. SOU VOL. XIV. 5 



