76 Messrs. Hancock & Attliey on a portion of 



specimen. We have in our possession teeth of this species 

 both ridged and grooved. They seem to vary in this respect 

 even when perfectly fresh ; but if a little eroded, the ridges are 

 much exaggerated and become quite sharp, giving a very 

 striking appearance to the tooth. In Loxomma the same va- 

 riability obtains : the teeth of that form are usually grooved ; 

 some, however, are ridged, while in others the ridges are 

 greatly increased by erosion. 



There is in Mr. Atthey's collection a pecidiar bone from the 

 shale at Newsham, that has been a great puzzle to us for a 

 long time. It was not till a nearly perfect mandibular ramus 

 of Loxomma was obtained that its true nature was solved. It 

 was then at once seen to be the articular piece, with a portion 

 of the dentary bone attached, of some large Labyrinthodont. 

 In form it closely resembles the same part in the ramus just 

 alluded to ; only it is very much larger, and must have be- 

 longed to a jaw equal in size to that from Fenton. In fact, 

 from its dimensions and massive character, it would seem 

 more than probable that this Newsham articular piece really 

 belongs to Anthracosaurus. 



The posterior margin of the fragment of the ramus in con- 

 nexion with the articular piece is perfect, and sweeps down- 

 wards in an even curve, Avliich, if continued a little further, as 

 k appears to have been, would give to the posterior part of the 

 jaw a depth of quite 4 inches — the measurement near the same 

 point of Mr. Ward's specimen. The articular piece stands well 

 up ; the neck is short and stout ; the process bearing the glenoid 

 surface is massive, and is transversely elongated, measuring 

 2\ inches long and an inch wide ; the glenoid cavity is deep, 

 and takes a slight sigmoid curve ; behind at the outer margin 

 there has been a stout jn'ojecting process ; and in front towards 

 the inner margin there has been a similar projection of the lip 

 of the articular cavity. It would therefore seem evident that 

 the attachment of the mandible to the tympanic trochlea must 

 have been very firm, rendering the movements of the jaw 

 secure and precise. Indeed the massive character of the 

 whole articular piece indicates great power, and is well cor- 

 related with the huge vomerine tusks and formidable dentition 

 of this species. 



The presence of Antliracosaurus in the Newcastle coal-field 

 does not rest merely on the occurrence of this articular piece. 

 We have already alluded to a large portion of the cranium 

 that was found at Newsham. This interesting specimen ex- 

 hibits numerous maxillary teeth and the two great vomerine 

 tusks so characteristic of this powerful Labyrinthodont. The 

 anterior extremity of a mandibular ramus with five teeth at- 



