1862.] OWEJf — REPTILIAN REMA.INS. 243 



breathers, there is such a known range of variation as to detract 

 from the value of the character of the degree of obtuseness of the 

 muzzle. Unfortunately, the occipital part of the skull, which would 

 have afforded the test of the mode of its articulation with the atlas, is 

 wanting. The Labyrinthodonts have a pair of condyles, as in Rana : 

 the Ganocephala, like Lepidosiren, show no bony joint between the 

 basi-occipital and atlas. 



The under surface of the bones forming the roof of the skull is 

 exposed in this specimen. As in Archegosaurus and Hylonomus, the 

 frontal (u) is separated from the orbital border (o, o) by the union of 

 the post- (12) and pre- (14) frontals. The temporal fossae were roofed 

 over with bone ; and these cranial bones show their external surface, 

 fig. 6, to be sculptui'ed with the beautiful and characteristic pattern 

 exhibited in the super temporal plate of the specimen oi Hylonomus, 

 fig. 3. This pattern may be seen on the cranial bones of some 

 ganoid fishes, and on those of Archegosaurus and Lahyrinthodon. 

 The orbits in Dendrerpeton are circular, divided by a bony tract of 

 more than their own diameter : they seem to have been midway 

 between the two ends of the skull; but the hinder part of this 

 is not complete in the specimen. The small nostrils are not midway 

 between the orbits and the muzzle, but nearer the latter. The few 

 teeth preserved at this part of the skull show the plication of the 

 base due to the entering folds of the cement, and yield, on a trans- 

 verse section (fig. 5 h), the same approach to the labyrinthic cha- 

 racter as in Archegosaurus. Their bases are confluent with the alveolar 

 depressions : there are no tusks as in Lahyrinthodon. 



A short straight bone, uniting with two other divergent ones, ap- 

 pears to be the ilium ; and I regard the specimen PI. X. fig. 7 as part 

 of the pelvis of Dendrerpeton : the ossified part of each of these bones 

 is a thin outer crust. The ilium, by its shortness and straight sub- 

 cylindiical rib-like form, agrees with that in Archegosaurus and in 

 modern Perennibranchiate reptiles. In Lahyrinthodon the ilium ex- 

 pands in some measure according to the Crocodilian type of the bone. 



The short proportions and simplicity of shape and structure of 

 the limb-bones combine, with the above-mentioned characters, to 

 demonstrate the Ganocephalous nature of this Nova-Scotian reptile 

 of the Coal-period. 



Dendrerpeton, like Hylonomus and Archegosaurus, shows the 

 affinity (shall we call it ?) or analogy to the ganoid fishes, not only 

 in the character of the cranial bones, but in the retention of a covering 

 of the body by ganoid scales : these are elliptic, smooth on their 

 inner surface, with a slight indication of a ridge, about half the 

 length of the scale, on the external surface, — at least, in certain of 

 the scales, and probably those along the back. 



The genus Hylonomus also, although with more minute and simple 

 teeth, had the skin defended by similar elliptic or suboval ganoid 

 scales. Much remains to be determined as to the structure of the 

 skull : nevertheless such cranial bones as have been obtained (PI. X. 

 figs. 3, <fc 5a, 6) exemplify the Ganocephalous sculpturing ; while the 

 arrested state of ossification of the endoskeleton and the characters 



