Osteology of Loxomma Allmanni. 39 



discovered, at about the same time and place, vertebra?, ribs, 

 and bones of the extremities, presumably belonging to the 

 same animal ; these were not very numerous, but were by far 

 the most common bones of Labyrinthodonts of any size that 

 were met with ; and they differed thus considerably from those 

 of Anthracosaurus and of Pteroplax, the only other large La- 

 byrinthodonts that have as yet been found in the Northumber- 

 land coal-field. 



The present paper contains a description of the cranium, 

 mandible, and teeth, and a notice of the vertebras, ribs, and 

 other bones, in the following order — viz. the upper surface of 

 the cranium, the under surface, the occipital surface, the man- 

 dible and teeth, and, lastly, the vertebras, ribs, and bones of 

 the extremities. 



I. The ujyper surface of the skull is represented in PI. IV. 

 Viewed thus the skull of Loxomma resembles generally that of 

 Archegosaurus and the Crocodilia, and of the latter the alli- 

 gator rather than the crocodile ; the snout, however, is broader 

 than that of the alligator, as is the whole skull, and the pos- 

 terior lateral expansions of the cranium for the articulation of 

 the mandible project a good deal further backward beyond the 

 occiput than in the above-named animals. 



The length of the skull along the median line, from the end 

 of the snout to the posterior edge of the occiput, is 12^ inches, 

 from the same point to the end of the lateral expansion above 

 the articular condyle 14^ inches. 



The breadth from side to side at the widest part, which is 

 a little in front of the posterior edge of the occiput, is 8 inches, 

 over the posterior ends of the orbital vacuities 7 inches, over 

 the anterior ends of the same 5 inches, and over the broadest 

 part of the snout 3^ inches. The snout is broadly rounded 

 off and rather flattened in front. 



This upper surface of the skull is all but perfect ; the sculp- 

 turing, the mucous grooves, the nostrils, the orbital vacuities, 

 the parietal foramen, the temporal fossae leading to the ex- 

 ternal ears, are all distinct. 



Each bone can (more or less clearly) be seen sur- 

 rounded by suture 5 the sculptured pattern on the surface is 

 the same as that described in the notice of Loxomma in the 

 ' Nat. Hist. Trans, of Northumb. & Durh,' vol. iv. pp. 201 

 (1871) and 390 (1872), namely " the peculiar honeycombed or 

 reticular structure ;" but it is distinguishable from that of the 

 other Labyrinthodonts. 



On examining closely the hollows or pits of this surface, 

 both of the cranium and mandible, one, two, or three minute 

 but well-defined openings are seen passing into the bone, but 



