242 PEOCEEDIlSfGS OF THE GEOLOGICAL SOCIETY. [Apr. 2, 



longitudinally fissured, but the fissures do not extend upon the 

 exserted crown. In their general characters, the teeth manifest at 

 least as close a resemblance to those of Ganocephala as of Lacertia 

 or any higher group of Beptilia ; whilst their mode of implantation, 

 with the structure and sculpturing of the bone, weigh in favour of 

 its relations to the lower and earlier order of the cold-blooded 

 Vertebrates. 



" No. 5. — Skin and dermal plates of Hylonomiis (?), probably 

 H. LyelUr 



The specimen so marked shows three oblong plates (PL X. a, h, 

 c, fig. 2), with a slightly concave surface, finely striate trans- 

 versely, and with one margin free, obtuse, and well defined. Con- 

 tinuous with this is a granulate surface, like shagreen, of small, 

 close-set, subelliptic scales or tubercles (cl) . 



Another portion of coal-shale shows a layer, and an impression of a 

 continuous part of the same layer, of integument (PI. X. fig. 1) which 

 has been defended by similar small and subimbricate scales. From 

 their state of preservation, these were probably bony or ganoid. I 

 do not know the evidence in proof of their belonging to Hylonomus. 



PL X. fig. 3 is a portion of the bones of the cranium, including 

 the frontal and parts of the prefrontal, postfrontal, parietal, post- 

 orbital, and supertemporal bones of probably a Hylonomus. They 

 show the skull to have been broad and much depressed : the super- 

 orbital border (o) is formed by the pre- and post-frontals. In most 

 of the bones, and especially the supertemporal plate, s, the outer 

 surface is sculptured according to the pattern shown in the skull of 

 Archegosaurus. 



PL X. fig. 4 is a portion of a jaw, with small equal teeth having 

 the characters of those of Hylonomus, and with a sculptured external 

 surface like that in PL X. fig. 3 and in PL IX. fig. 15. 



Passing over the interesting examples of probably the food of the 

 small reptiles, shown in No. 5 {Pupa vetusta, Dawson) and No. 7 

 (Xylobius sigillarius, Dawson), I come to 



^' No. 8. Loose specimens of Dendrerjpeton Acadianum, Ow. 

 (a nearly complete skeleton)." 



The chief addition to the evidence already recorded of the charac- 

 ters of this reptile* are, 1st, the incompletely ossified conditions of the 

 endoskeleton, manifested even in the slender ribs, which have their 

 cavities filled with matrix, as formerly with the primitive cartilage ; 

 2nd, the shape of the head (PL X. fig. 5 a) ; 3rd, the superficial 

 markings of the cranial bones (fig. 6) and scutes ; 4th, the batrachian 

 type of the ilium, and probably of the pelvis, fig. 7. 



The skull (PL X. fig. 5 a) is broad, depressed, obtusely rounded 

 anteriorly, rather Labyrinthodontal than Archegosaural in shape; 

 although, in the species of both these early types of batrachian air- 

 * Quart. Journ, Geol. Soc. vol. ix. p. 64, &c. 



