



140 PALAEONTOLOGY OF ILLINOIS. 



extended backward, the exterior or first digit is shortest, and a little less than 

 the second. This is equal to two and one-half phalanges of the fifth (reckoning 

 from its base) or the proximal pair of phalanges of the fourth. The fifth is a 

 little shorter than the third, which is scarcely equal to the three proximal 

 phalanges of the fourth. The number of phalanges 3 — 3 — 4 — 5 — 4: among 

 the Salamanders the last two numbers are usually 4 — 3. They are without 

 condyles, but exhibit one or two emarginations at their articulating surfaces. 

 The length of the basal phalanx of the first digit is two-thirds that of the second ; 

 the latter equals that of the fifth and the second phalanx of the fourth; these 

 are very little shorter than the basal of the third and fourth. The terminal 

 phalanges are elongate acute, those of the first and fourth slightly curved. 

 They are much less obtuse than in Salamanders, and the animal has probably 

 had weak claws; of these no trace remains. 



A few traces indicate that the dermal integument was covered, on the ante- 

 rior part of the body, at least, with small and sub-granular scales. There have 

 been abdominal scales arranged in narrow imbricate series, directed inward and 

 posteriorly. Traces of plates are wanting, excepting a small fragment lying 

 beside the cervical vertebras. 



The length of this species from the sacral centre to the interscapular region 

 was 13 lines ; from the latter point to the end of the muzzle, 12 lines; to the 

 occipital border, 4-5 lines. Longitudinal diameter of orbit, 3 lines; frontal 

 breadth, 2 lines; from border of orbit to border of nostril, 1-5 lines; breadth 

 of cranial table, 3—75 lines. Length of humerus, 3 lines; of femur, 3-6 lines; 

 of tibia, 2-3 lines; of fifth digit, 2-75 lines; of fourth. 4-2 lines; of first. 1-8 

 lines. The portion of the tail preserved measures 5-2 lines. 



If we compare the peculiarities of this genus with those of the Batrachia of 

 the same period, we find it to be distinguished, independently of the ordinal 

 characters, from such genera as Osteophorus, 31elosaurus Sderocephalus, Xestor- 

 rhgfias, Baphetes and Brachi/ops, by the absence of the sculpturing of the cranial 

 bones, the lack of dermal shields, characteristic of most of these, and by the 

 presence of cranial and palpebral scales. The crania of the first genera are 

 much more elongate, and imitate those of some Crocoililia. Similar differences 

 exist between the Illinois Batrachian and Devdrerpeton, Owen ; the latter pos- 

 sesses, also, a double row of teeth. BJj/lonomus, Dawson, supposed to possess 

 Lacertilian affinities, exhibits ribs and biconcave vertebrae. The ribs of Teler- 

 pcton will distinguish it also. The only genus as yet known to approach closely 

 that under consideration has been described by Prof. J. Wyman under the 

 name of Raniceps.* This animal is only known from a study of the inferior 

 aspect of a portion of the skeleton ; nevertheless it is certainly differci.t, being 



* Silliman's Journal Sci. Arts, 1858, p. 158. 





