282 H. G. SEELEY ON A POKTION OE 



Chelonia, present many analogies in the perforations, in the struc- 

 ture of the jaw, and in the sculpture of the hones. But in the 

 absence of more important parts of the skeleton, no conclusions can 

 be drawn from these resemblances. 



The species indicated by this specimen is almost identical in size 

 with the fragment attributed by Mr. Miall to Labyrinthoclon pachy- 

 gnathus, and, so far as I can judge from figures, resembles that fossil 

 closely both in form and ornamentation. But the depth and outline 

 of the postarticular part of the jaw, and the differences of sculpture 

 in the lateral subarticular ornament, supply characters for distinc- 

 tion which, if the Warwickshire specimens are accurately figured, 

 must separate the Dorsetshire fossil as a distinct species : this I 

 propose to name Labyrintliodon Lavisi, in honour of its discoverer. 



Associated Fragments. — Within a yard or two of the spot where 

 the jaw was found, Mr. Lavis picked up several other Labyrintho- 

 dont fragments, which he supposes, with good reason, to have been 

 portions of the same skeleton. These comprise two small pieces of 

 bones from the upper part of the skull, which are too imperfect to 

 be determined with certainty at present, though one forms a portion 

 probably of the orbit of the eye, and the other shows a portion of a 

 narrow channel of the kind which has been called mucous groove : 

 its radiated sculpture is finer than on the other specimens ; and it 

 may belong to a young animal or a small species. Another com- 

 pressed curved bone about 2J inches long, || inch deep at one end, 

 narrowing along the curve, and less than \ inch thick, I am disposed 

 to regard (if Labyrinthodont at all) as possibly a vomer. The concave 

 border of the specimen appears to have been palatal. Along it, and 

 on part of the adjacent side of the bone, extend three or four ill- 

 preserved rows of small conical teeth, which vary in size. These 

 present a suggestive resemblance to the rows of teeth on the spe- 

 cimen figured by Prof. Huxley, and named Hyperodapedon, espe- 

 cially as some of them are similarly worn down ; and it is possible 

 that this fragment may pertain to that genus. 



Two other specimens are portions of thoracic plates. A narrow 

 fragment, 2\ inches long, probably belongs to the median thoracic 

 plate ; while the principal fragment, 3 inches long and 1| inch 

 wide, may be the right thoracic plate. It is thin, and marked by 

 the usual radiated sculpture, but has the broad external border 

 compressed and smooth. 



Other smaller but imperfect plates were found, which are marked 

 with shallow pits which do not become elongated into grooves. 



Another portion of bone may be a segment from the upper part of 

 a strong rib. 



A chevron bone (fig. 4) shows the articular surfaces on one side, 

 which prove it to have been articulated between two vertebrae, as in 

 most of the Reptilia and Palaeosauria. 



Portions of dense cylindrical or more compressed bones, having 

 the appearance of weathered teeth, were found ; but the transverse 

 sections which Mr. Cuttell has endeavoured to prepare are too thick 

 and opaque to demonstrate their real nature. 



