Mr. H, J. Carter on a neiv Genus of Sjfonges. 189 



structure of the teeth demonstrate this since we have become 

 acquainted with these features in that genus. 



The fragment, which is upwards of 2| inches long, 1^ inch 

 wide behind, and | inch wide in front, is the anterior portion 

 of the right mandible ; it has attached to it five teeth ; in front 

 it is perfect ; the posterior portion is broken away close to the 

 fifth tooth, which, though much injured, appears to be about 

 half an inch long. The three next in advance are not quite 

 so long, and are separated from the fifth and from each other 

 by considerable spaces, and from the tooth in front by a space 

 f inch in length. This frontal tooth, which is perfect, is half 

 an inch long and ^ inch wide at the base ; it is placed a 

 little way from the extremity, where there is a depression, but 

 whether for the reception of the base of a tooth cannot be de- 

 termined. The surface of the teeth is ridged, particularly 

 towards the base, agreeing in this respect with those in the 

 Scotch specimen ; they are a little compressed above ; and one, 

 which is tolerably perfect, has the apex slightly carinated. 



On making a section of one of the teeth, it is quite obvious 

 that the ridges on the surface are owing to erosion, if not 

 entirely, at least mainly, and that the internal structure agrees 

 very well with that of Anthracosaurus when allowance is 

 made for the variation caused by the sections not being made 

 at the same part. Our section was made a little way up 

 the tooth, while those of the Scotch specimen were, as we 

 have already explained, evidently made close to the base. 



There can therefore be little doubt that this fragmentary 

 mandible really belongs to Anthracosaurus. We have, then, the 

 satisfaction of recording the occurrence in the Northumberland 

 coal-field not only of a considerable portion of the cranium, but 

 likewise of a large fragment of the jaw of this rare fossil. 



The large sternal plate, nearly 5 inches long, described in 

 our paper on Pteroplax'^^ is probably that of Anthracosaurus ; 

 it was found in the same locality, and this is the only large 

 Labyrinthodont occurring in the Newsham shale to which it 

 can at present be assigned. We also possess some ribs and 

 vertebrae which perhaps belong to the same animal. 



XXI. — On Grayella cyathophora, a new Oenus and Species 

 of Sponges. By H. J. Carter, F.R.S. &c. 



[Plate VII.] 



About a fortnight since, Dr. J. E. Gray kindly sent me a 

 specimen of a marine sponge, Avith the request that I would 

 * See Annals of Nat. Hist. ser. 4. vol. i. p. 277. 

 Ann. & Mag. N. Hist. Ser. 4. Vol.w. 14 



