18 THE EXTINCT BATRACHIA, REPTILIA 



eton which was the type of the present genus. The species thus constituted is 

 represented by five specimens and their reverses, and a fifth may be added with much 

 probability. 



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



The extremities of the vertebras are denply concave, but the centra are so long as to prevent the concavities en- 

 tering more than one-fifth of the latter, each. The diapophyses are behind the middle, and are broad, curved back- 

 wards, and acuminate as in Amphiuma. The centra have a prominent median line below, with a longitudinal con- 

 cavity on each side. Five of them a little exceed an inch in length. Neural spines moderate. The hu- 

 merus is longer than the coracoid, and is considerably dilated distally ; the coracoid slightly dilated at its superior 

 extremity. The dermal armature commences immediately behind the head, and forms a band of 14 lines in width ; 

 measuring across the spine-like scales, in a width of a line, four cylinders may be counted. The external portions 

 are curved backwards, the interior nearly straight, those of the anterior series more delicate than the posterior. 



The head is wedge-shaped, with regularly acuminate sides. The top of the cranium is somewhat broken in the 

 specimen ; the portions preserved are smooth, and the longitudinal suture is distinct for a considerable distance. 

 The angle of the mandible is produced considerably behind the occiput, and is enlarged and rounded. The end of 

 the muzzle is broken away, and the region of the orbits so fractured as to render their precise location uncertain. 

 The superficial layer of the cranial bones is nowhere clearly visible, so that it cannot be ascertained whether it is 

 sculptured or not. The quadrate bone projects well posteriorly. Some fragments indicate small cylindric teeth, as 

 in Amphibamus, but they are not characteristic. 



Measurements. Lines. 



Length cranium without muzzle. 17.3 



Width do posteriorly, 11.5 



Length of the coracoid, 2.1 



Length humerus, 2.5 



Length of sixth vertebra from skull, 3 



Extent diapophyses, 3.S 



Width centrum, 1.5 



The characters of the genus are further shown by a part of another individual in the same coal slate matrix. 

 The cranium and anterior portion of the vertebral column only are preserved, the latter so much injured as to render 

 the vertebral characters very obscure. As in the other, the bristle-like scales extend along the dorsal retriou to 

 near the cranium. The anterior | of the ventral side shows a large number of oval scale-like bodies, which 

 belonged undoubtedly to the animal, and were probably dermal scales. They are, however, neither regular in 

 from nor position. Close behind the head two or three long bones of the fore limbs have been exposed. They are 

 slender and similar to those of the last specimen. 



The cranium, though without the muzzle, shows its long wedge shape. The maxillary bone cannot be distin- 

 guished, nor can the orbits be made out. One ramus mandibuli is pretty well preserved ; it shows no coronoid pro- 

 cess. Thirty-one teeth may be counted on a portion a little more than one-third its length. The anterior eleven of 

 these are abruptly longer and stouter than the others. They are all, except a few most anterior, in pairs, i. e., with 

 a slight vacancy between every two. The larger ones where broken at the bases exhibit a moderate pulp cavity ; 

 the smaller, a large one extending to near the lip. Several, though not all of the larger teeth, display a shallow 

 groove on the external face to near the tip, which is probably owing to pressure and a partial crushing. The 

 points of the larger teeth are more abruptly acute, and turned abruptly _backwards. A portion of their increased 

 length (.35) is to be attributed to the splitting off of the external dentary margin, and the exposure of the roots. 

 No alveoli are shown, and the dentition is probably by anchylosis of expanded base as in true Labyrinthodonts . 



A third series, Nos. 26, 29, Mus. Newberry, of dorsal vertebras is without head or limbs. The vertebrae are 

 elongate, three of them extending over 2.10 mm. The neural spines are longer than high, and are nearly in 

 contact at their margins ; each is marked by about five obtuse vertical ribs. A fractured section of the abdom- 

 inal dermal spines in place, displays at least six superimposed layers of them. 



