166 Mr. T. Atthey on Antliracosaururf liusselll. 



In refeiTing to the description of Pteroplax, H. & A., in the 

 'Annals,' ser. 4, vol. i. plates xiv. & xv. fig. 2, 1 find it neces- 

 sary to correct what now appears en-oneous in that paper. 

 The sternal plates, figured and described as belonging to Ptero- 

 plax, I now think cannot properly be attributed to that animal. 

 That they may have belonged to Anthracosaurus or Loxomma 

 is more probable 5 but even that is doubtful. Fig. '6 of 

 plate xiv., called prffimaxilla of PteropJax, does not belong 

 to Pteroplax at all, but is a praimaxilla of Loxomma All- 

 manni. Plate xv. fig. 2 is named as a vertebra of Pteroplax^ 

 but is in reality a vertebra of Anthracosaurus 5 and in our 

 description of it we noticed its resemblance to the vertebra 

 figured in Qu. Journ. Geol. Soc. vol. xix. p. 63, 186.3, as that 

 oi Anthracosaurus by Prof. Huxley. 



Three crania (one in the Leeds Museum and two in my 

 cabinet) are all we know as yet of this rare amphibian. On 

 one of these latter lie two ribs which most probably belonged 

 to the same animal. That on the upper surface is entire and 

 much like a rib of Loxomma^ but smaller ; both head and 

 tubercle are well shown : that on the under surface cannot 

 well be described, as it is not sufficiently exposed. All three 

 specimens are from Newsham, near Blyth, Northumberland. 



The general configuration of the under surface of the skull 

 is much the same in Loxomma and in Anthracosaurus^ but ir 

 very different in Pteroplax. The vomers pass much further 

 forward in Anthracosaums than in Loxomma. Their anterior 

 margins in the latter are just in front of the vomerine tusks, 

 and are sutured to each other on the median line ; by their 

 outer margins they join the maxillai-ies, and behind the palate- 

 bones; whilst in Anthracosaurus the anterior end of the palate- 

 bone lies in between the vomers and the maxillaries. The 

 posterior part of the palate is much the same in Anthracosaurus 

 and Loxomma^ but, so far as I can ascertain, is probably very 

 different in Pteropilax. 



Whether Anthracosaurus possessed epiotic horns like Lox- 

 omma and Pteroplax is not determinable, the specimen being 

 deficient at these parts. 



The teeth of Ayithracosaurus differ much from the teeth of 

 Loxomma ; they are slightly oval in outline and altogether 

 stronger than the latter, which are much flattened. The teeth 

 of both in section show most beautiful Labyrinthodont struc- 

 ture. The teeth of Pteroplax have not as yet been found. 



The vertebrse and ribs in Anthracosaurus Siud Loxomma are 

 of large size, very strong, and most difficult to distinguish from 

 each other when found separate. None of the vertebrje of 

 Pteroplax have ever been discovered. 



