EXTINCT BATRA.CHIA. 387 



The same dimensions in 0. remex are .012; extent of spines, .02. While 

 this species is smaller than the latter, it is larger than any known Ptyo- 

 nius ; its elongate vertebrae are most like those of Oestocephalus. 



A cranium of a much smaller individual than any of the 0. remex, 

 found by Dr. Newberry in 1874, probably belongs to another species, 

 but without other parts even the generic reference is uncertain. The 

 great size, especially of the posterior part of the lower jaw, produces a 

 marked resemblance of the toad to that of a diminutive crocodile. 

 Length, .042; depth behind, .014; depth of lower jaw behind at coro- 

 noid, .006. (See pi. 44, fig. 3.) 



^ Hyphasma, Cope. 



Proceed. Academy, Philada., 1875, p. 16. 



Vertebrae osseous, the jjosterior dorsals, and probably the caudals, fur- 

 nished with fan-like neural spines ; limbs unknown — ? wanting. Tho- 

 racic shields present Ventral armature, consisting of rhomboidal scuta, 

 forming packed rows arranged in chevrons, directed backwards, on top 

 of which are the usual rod-like scales arranged in packed chevrons, with 

 the angle directed forward. 



The general appearance of the type of this genus is that of a Plyonius, 

 but the ventral armature is different from any thing observed in the 

 known genera of this group. The larger external scuta are like those 

 of the species of Colosteus, but their series have a different direction. 

 The inner chevrons are those of many other genera. 



Hyphasma laevis, Cope. 



In the only known specimen the vertebra have low and squarely 

 ' truncate neural spines to near the head, and some distance anterior to 

 the tail they are quite conspicuous and delicately line-grooved. The 

 body is slender and probably limbless. The thoracic scuta are large and 

 close to the head; the median is produced at both ends, but chiefly ante- 

 riorly, while the lateral are narrow; all are without sculpture. The 

 head is seen from below. The mandibular rami are not so slender as in 

 most species of Plyonius, but are rather stout. They are a little incurved 

 clistally, so that the form of the muzzle is somewhat narrowed, but not 

 produced. The teeth are not visible. Ten rows of the outer layer of 

 scuta in .005 m. 



Length of specimen, .068 m.; width of do., .008; length of seven ver- 

 tebrae, .015; length of median thoracic scuta, .010; width of do., .004; 

 width of lateral do., .002; length of mandibular ramus, .012. 



