516 Mr. Owen on species of 



of the tooth of the Labyrinthodon laniarius from the Coton-end quarry, he was so 

 good as to bring up to London the whole of the collection of reptilian fossils from 

 the New Red Sandstone formation of Warwick and Leamington, which are de- 

 posited in the museums of those towns, and obtained for me the same liberal permis- 

 sion as on the former occasion, to apply to any of the teeth which these fossils 

 might contain the microscopic test. 



Amongst these fossils, two distinct species of the genus Labyrinthodon were at 

 once evident, and were represented by portions of upper and lower jaws, an anterior 

 frontal bone, two vertebrae, one of which is nearly entire, a sternum, a fractured 

 humerus, an ihac bone with a great part of the acetabulum, the head of the femur, 

 and two ungueal phalanges. The maxillary fragments containing teeth, besides the 

 agreement in dental structure, as I have ascertained by microscopic examination of 

 sections from each fossil, likewise correspond with the German Labyrinthodon in the 

 relative size, mode of implantation, and arrangement of the teeth : the maxillary 

 teeth, e. g., are almost all of moderate and equal size, and these are closely arranged 

 in a single straight row, each tooth being implanted by a broad base in a distinct 

 but not deep socket ; whilst the remaining teeth, two or three in number on each 

 side of the upper and lower jaws, are of much larger size, and are situated less 

 regularly at the anterior part of the dental series. 



Labyrinthodon Leptognathus. 



I shall commence with the description of the fossils from the Coton-end sand- 

 stone quarries, near Warwick, which indicate the smaller species of Labyrinthodon, 

 to which the name of leptognathus is here given, in reference to the slender charac- 

 ter of its long lower jaw. 



Upper Jaw. — ^The first of these fossils (PI. XLTIL fig. 1, 2, 3.) is the anterior part of 

 the left side of the upper jaw, including the nasal bones. It shows that the maxillary 

 or facial division of the skull was broad, much depressed, and flattened, resembling the 

 skull of the gigantic Salamander, and also that of the Alligator, and having the outer 

 surface of the bones strongly sculptured by depressions and furrows as in the Croco- 

 dilian family. The portion of jaw here described contains the alveoli of the ante- 

 rior moiety of the single row of small teeth and the base of one of the great anterior 

 tusks, which ranges in the same line with the small serial teeth, but is directed 

 obliquely backwards, the smaller serial teeth projecting more vertically from the 

 alveolar margin of the jaw, and being slightly inclined outwards. In a few places 

 the contiguous teeth are in place, but throughout the greater part of the series only 

 those of alternate sockets. The base of the tooth projects directly from the outer 

 wall of the socket, there being no alveolar ridge external to it. The alveolar series 

 in this specimen contains in an extent of two inches three lines, thirty-one sockets 

 including the large anterior tooth. The base of the smaller tooth is subcompressed 



