294 PROCEEDINGS OF THE GEOLOGICAL sociExr. [May 7, 



which are connected with its antero-lateral edges in Labyrinthodonts, 

 in situ. This specimen is represented in fig. 2. 



The median plate is 5| inches long, by at least 2| inches broad at its 

 widest part. Its anterior extremity is broken away, but, I think, 

 not for any great extent. Its posterior end (almost entire) is abruptly 

 truncated, and |- of an inch wide. It continues of about the same 

 width for nearly an inch, and then its edges, becoming thinner, 

 sweep outwards with a sKght curve until the plate attains the 

 maximum width I have mentioned, at a distance of 2^ inches from 

 its hinder end. Here it becomes so completely overlapped by the 

 lateral plates, that no more can be said about its lateral contour. A 

 fragment of a somewhat larger plate of the same kind leads me to 

 believe, however, that the bone does not attain any much greater 

 width anteriorly. The middle of the plate is thicker than its edges ; 

 and shallow, slightly reticulated grooves diverge from the concealed 

 centre of the bone, towards its thin edges, before reaching which 

 they are lost. The form of what remains of the lateral plates is 

 given in the figure; they are thicker internally, and exhibit the 

 same radiating grooved sculpture as the median plate. The grooves 

 diverge from the middle of the inner margin of each plate. 



2. Description of a new Lahyrinthodont (Pholidogaster 

 pisciformis, Huxley). 



Loxomma is not the only Lahyrinthodont in the Edinburgh coal- 

 field. Some years ago a remarkable fossil was obtained from the 

 same district by Sir Philip Egerton and the Earl of Enniskillen, but 

 as, on mature consideration, it appeared to them not to be a fish, it 

 was handed over to the British Museum. My attention was long 

 ago drawn to this specimen by Mr. Davis, of that Institution, who, 

 at the same time, very justly remarked upon the resemblance in the 

 arrangement of the scales between this animal and Archegosaurus. 



A recent careful study of the fossil has fully borne out Mr. Davis's 

 suspicion, and has convinced me that the fossil is an Amphibian allied 

 to Archegosaurus, though it differs from the latter in the form of the 

 head, the extent to which the ossification of the vertebral column 

 has proceeded, and in the characters of its dermal armour. It shares 

 with Archegosaurus, however, the peculiarity of having its over- 

 lapping scales arranged in double oblique series between the pectoral 

 and pelvic arches only, whence, and on account of its fish-hke form, 

 I propose the name of Pholidogaster pisciformis for the genus and 

 species. 



The specimen (PI. XI. fig. 3) is in a very indifferent state of pre- 

 servation, and is so disposed in the matrix as to show the under or 

 ventral surface of the head and body. Its total length is about 43 

 or 44 inches, of which the head occupies less than -i-th, the ramus of 

 the lower jaw being 7 inches long. At its hindmost or widest part, 

 the head measures about 5 inches in transverse diameter. In shape it 

 resembles an oval bisected along its short diameter, the snout being 

 completely rounded off. In front of the symphysis of the mandible, 

 the under surface of the premaxiUa is visible, bearing the stumps of 



