REPTILIA : OPHIACODON 81 



OPHIACODON 

 Marsh, Amer. Jour. Science, XV, 411, May 3, 1878. 



Ophiacodon mirus Marsh, loc. clt. 



A third genus of reptiles allied to the last described [Sphenacodon] is indi- 

 cated by various well-preserved remains from the same locality. The teeth are 

 all carnivorous in type, conical in form, and all are similar. Those in the 

 anterior part of the jaws are recurved, and in general shape resemble those of 

 serpents. The rami of the lower jaws were united only by cartilage. The 

 vertebrae are very deeply biconcave, and even perforate, and the intracentral 

 bones large. In the present species the teeth are nearly smooth, and some- 

 what compressed. 



The following measurements indicate the size of this reptile: 



Extent of anterior sixteen teeth in dentary 75 mm. 



Extent of anterior five lower teeth 20 



Height of crown of fourth lower tooth 10 



Depth of lower jaw at symphysis 15 



Extent of seven anterior maxillary teeth 33 



Height of crown of first maxillary tooth 9 



Antero-posterior diameter of crown 3 



This species was about as large as those described above, and is from the 

 same geological horizon in New Mexico. 



The type specimen of this genus and species, a mandible, is 

 figured in Plate XXXI, Fig. 3. Some of the long teeth had been 

 gummed together with mucilage, but other fragments were still 

 separate, and yet others have not been recovered. Fragments 

 of an upper jaw from which the measurements had been taken I 

 have not thought necessary to figure. In addition, I find three or 

 four mandibular bones and several maxillae, all of them of a 

 somewhat larger size than is the type specimen. All of these 

 specimens are from among the original collection studied by 

 Marsh. I find no other evidences of the skull among the material 

 acquired later. 



With this genus I associate provisionally a considerable number 

 of limb bones and vertebrae which were associated with the type 

 specimen, including five humeri, the best and largest of which I 

 have figured; a complete radius and a complete ulna, and parts of 

 two or three others of each bone; at least five scapulae, none of 



