396 



PALEONTOLOGY OF OHIO. 



The muzzle is broadly rounded, as in T, obtusa, and the premaxillary 

 teeth are relatively much larger. The bones are sculptured with deli- 

 cate, acute, radiating, and inosculating ridges. The maxillary bone is 

 preserved for the length of one inch ; its teeth are smaller than those of 

 the premaxillary bone ; I count four in a line, which have a simple 

 conic crown. The external surface of the maxillary is not very strongly 

 sculptured. The orbits and nares are not well defined in the specimen. 



Fm. 11. 



TUDITANUS OBTUSUS, Cope. 



Proceed. Acad. Nat. Sciences, Philad., 1868, 213; Transac. American Pliilos. Soc, 

 XIV., p. 12. 



This species is known by two partially preserved crania. The supe- 

 rior surface is exposed, the outlines of the jaws and orbits are well pre- 

 served, with the occipital condyles. 

 The OS quadratum is directed ob- 

 liquely backwards, and the angle of 

 the mandible extends to a line a lit- 

 tle behind that of the occipital con- 

 dyles. The zygomatic arch exists in 

 a position similar to that in which it 

 may be seen in a few genera of Anura, 

 as Discoglossus and Pelobates. It ex- 

 tends downwards ai^d forwards from 

 the suprasquamosal to the maxillary 

 region, but whether it is homologi- 

 cally squamosal or malar the speci- 

 men does not show. The postorbital 

 is present as well, and with the last, 

 and the supratemporal, forms the 

 bony roof of the temporal fossa. A piece which may be the pre and post- 

 frontals combined, borders the inner superior margin of the orbit; it 

 widens posteriorly, where it has contact with the parietal, etc., and nar- 

 rows in front. Supraoccipitals form together a broad triangle on the 

 upper plane of the cranium, of less extent than the adjoining supratem- 

 poral. These elements are pitted, and towards their margins radiate 

 grooved. 



The general form of skull is elongate behind, and much shortened in 

 front of the orbits. The orbits are thus in front of a line equally divid- 

 ing the cranium transversely, while in the Dendrerpeton acadianum they 



