Geological Society. 181 



fragments of bone, some of which, belonging to a species of Lahij- 

 rlnthodon, would bo described by Prof. Seeley. The author men- 

 tioned that he had received from the Rev. S. H. Cooke some frag- 

 ments of bone obtained by him twenty years ago from this same 

 " ossiferous zone." Mr. AVhitaker's specimen of Hyperodapedon 

 was also obtained from the Upper Sandstone. 



" On the Posterior Portion of a Lower Jaw of Lahyriniliodon 

 (L. Lavisi) from the Trias of Sidmouth." By Harry Govier Seeley, 

 Esq., F.L.S., F.G.S., Professor of Physical Geography in Bedford 

 College, London. 



After referring to the doubtful position of the Labyrinthodontia 

 in the system, and expressing his doubts as to the occurrence of the 

 genus Mastodonsaunis in Britain, the author proceeded to describe 

 in detail the posterior part of the right ramus of the lower jaw of a 

 Labyrinthodont, obtained by Mr. Lavis from the ossiferous zone of 

 the Trias near Sidmouth, the position of which was described by 

 that gentleman in the preceding paper. The specimen, which is 

 13 inches long, and perfectly free from matrix, shows that the 

 lower jaw in Labyriuthodonts not only contains articular, angular, 

 and dentary elements, as hitherto supposed, but also separate sple- 

 nial and surangular elements, and probably a distinct coronoid 

 bone. These bones were described in detail ; and the author re- 

 marked that although they are somewhat reptilian in aspect and 

 arrangement, they are not very suggestive as to the affinities of 

 Lahyrintliodon. They surround a central hoUoAv space, which no 

 doubt received the primitive cartilage round which the bones were 

 ossified ; and the persistence of this character would seem to be a 

 link rather with the lower than with the higher Vertebrata. The 

 jaw differs from the Batrachian mandible in possessing well de- 

 veloped angular and surangular elements ; and some reptiles, such 

 as Crocodiles and the marine C'helonia, present analogies in the per- 

 forations, the structure of the jaw, and the sculpture of the bones. In 

 size the specimen is almost identical with that figured by Mr. Miall as 

 belonging to Labyrinthodonpachygnaihus ; but the depth and outlines 

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

 of the lateral subarticular ornament, furnish distinctive characters 

 which lead the author to describe the present specimen as represent- 

 ing a new species, which he names, in honour of its discoverer, 

 Labyrinthodon Lavisi. The author briefly noticed several other 

 bones and fragments obtained by Mr. Lavis in the same locality, 

 some of which probably belonged to the same skeleton. 



"On the Discovery of Melonites in Britain." Ey Walter Keeping, 

 Esq. 



The author described a specimen from the Carboniferous lime- 

 stone of Derbyshire in the museum of the Geological Survey, which 

 displays numerous plates belonging to the test of a large Echinoid, 



Ann. & Mag. N. Hist. Ser. 4. Vol. xviii. 13 



