MK. T. ATTHET OX ANTHBACOSAUEUS RUSSELLI. 331 



matter, probably from the intestines ; and mixed up with it are 

 a palate-tooth, a rib, and several fragments of scales, belonging 

 to Ctenodus. 



Can it safely be inferred from these accompaniments that 

 Ctenodus formed at least a part of the food of Anthracosaurus ? 



Note. — Of the three large Labyrinthodonts as yet found in the 

 Northumberland coal-field, Anthracosaurus is by far the largest. 

 The general arrangement of the separate bones which form the 

 upper surface of the cranium is much the same in both Anthra- 

 cosaurus and Loxomma ; but it differs considerably from that of 

 Pteroplax, whose entire cranium, so far as we know from speci- 

 mens up to the present time obtained, is composed of the bones 

 corresponding to those which form the centre or middle posterior 

 part of the crania of the two former, viz., the frontals, parietals, 

 occipitals, postfrontals, squamous, and epiotics. The posterior 

 lateral expansions, composed of postorbital, supratemporal, quad- 

 rate, and quadrate- jugal bones, do not exist in this very in- 

 teresting amphibian; the premaxillary, maxillary, nasal, and 

 prefrontal bones also, which form the anterior extremity of the 

 cranium, have been broken off, strange to say, from all the three 

 specimens as yet known. Pteroplax therefore differs consider- 

 ably in size, in outline, and in many details from both Anthra- 

 cosaurus and Loxomma. 



In referring to the description of Pteroplax, H. and A., in the 

 " Annals," Ser. 4, Yol. I., Plates XIY. and XY., fig. 2, I find it 

 necessary to correct what now appears erroneous 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 ; but even that is doubtful. Fig. 3 of Plate XIY., 

 called premaxilla of Pteroplax, does not belong to Pteroplax at 

 all, but is a premaxilla of Loxomma Allmanni. Plate XY., fig. 2 

 is named as a vertebra of Pterovlax, but is in reality a vertebra 

 of Anthracosaurus ; and in our description of it we noticed its re- 

 semblance to the vertebra figured in Quart. Journ. Geol. Soc, Yol. 

 XIX., p. 63, 1863, as that of Anthracosaurus by Prof. Huxley. 



