234 Beports and Proceedings — 



These bones were described in detail; and the author remarked that, 

 although they are somewhat reptilian in aspect and arrangement, 

 they are not very suggestive as to the affinities of LahyrintJiodon. 

 They surround a central hollow 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-developed angular and 

 surangular elements ; and some reptiles, such as Crocodiles and the 

 marine Chelonia, present analogies in the perforations, 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 

 LahyrintJiodon pacliygnathus, but the depth and outlines of the postar- 

 ticular part of the jaw, and difi'erences in the sculpture of the lateral 

 subarticular ornament, furnish distinctive characters which lead the 

 author to describe the present species as representing a new species, 

 which he names, in honour of its discoverer, Lahyrinthodon 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. 



3. " On the Discovery of Melonites in Britain." By Walter 

 Keeping, Esq. Communicated by Prof. T. M'Kenny Hughes, F.G.S. 



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, 

 considered by him to be a new species of the genus Melonites, 

 hitherto regarded as peculiar to America. The author proposed to 

 call this species Melonites Tltheridgii, and he described it as possess- 

 ing a more or less spheroidal test, about seven inches in diameter, 

 composed of very thick plates, arranged in five ambulacral and five 

 interambulacral areas, all the plates being ornamented with minute 

 tubercles for the support of spines. The interambulacral areas were 

 probably about twice as broad as the ambulacral, and composed (at 

 the equator) of about nine ranges of plates, the marginal ones pen- 

 tagonal, the rest hexagonal, articulating with each other by faces 

 varying from a right angle to one of 30°. The ambulacral areas 

 were broad, each formed of two convex ribs separated by a meridional 

 depression running from mouth to anus, and each rib (half-area) com- 

 230sed of six or seven ranges of irregular plates, each perforated by a 

 pair of simple pores. The tubercles are minute, imperforate, without 

 boss, and of two orders, the larger surrounded by a smooth areola, 

 bounded by an elevated ring. The spines are small, tapering, 

 coarsely sulcate, with a prominent collar round the articular end. 

 A second specimen exists in the British Museum. The species 

 difi'ers strikingly from the North American Melonites multiporus in 

 the characters of the ambulacral areas, which have 12-14 ranges of 

 plates, and are divided by a meridional furrow in the new species, 

 and only eight ranges of plates, with a median ridge formed of plates 

 twice as large as the rest in M. multiporus. 



4. " Note on the Phosphates of the Laurentian and Cambrian 

 .Eocks of Canada." By Principal Dawson, LL.D., E.K.S., F.G.S. 



