Epports and Proceedings — Geological Society of London. 233 



matters removed in solution, I have shown that we must reduce the 

 time to one foot in 4500 years." To take notice of a verbal slip, 

 confounding time with feet-per-year, may be making a mountain 

 of a molehill. If I have done that, at any rate I have achieved a 

 success in mountain-building. 



In chapter x. our author gives very good reasons for considering 

 the globe to contain a sufficient supply of heat for all the purposes 

 of his theory. But he has made a mistake in supposing (as by 

 working out his figures he seems to have done) that, if the tempera- 

 ture of the whole were reduced to zero Fah., all its heat would be 

 exhausted. To accomplish that result, it would need to be reduced 

 460° Fah. lower still. 0. Fisher. 



I2,E:P0K,TS JiJlSTlD DPI^OGE:EIDI3^^3-S. 



Geological Society of London. 



I.— March 9, 1887. — Professor J. W. Judd, F.E.S., President, 

 in the Chair. — The following communications were read : — 



1. "On Chondrostens acipenseroides, Ag." By James W. Davis, 

 Esq., F.G.S. 



Sir P. Egerton described two species of Chondrosteus from the Lias 

 of Lyme Regis, viz. C. acipenseroides, Ag., and C. crassior. Eg. The 

 author describes an unusually fine specimen from the same locality, 

 44 inches long, the head, trunk, and tail being exceptionally complete, 

 whilst a considerable portion of the elements of the vertebral column 

 is preserved. 



The head is proportionately large and deeper than the body of the 

 fish. It has an almost circular outline with a diameter of about 

 9 inches, but the snout has been broken off during extraction. The 

 cranium was protected by dermal bones or scutes. The anterior 

 portion of the head, beneath the orbit, does not exhibit any traces of 

 external defence, thus differing from existing Sturgeons. The f rentals, 

 postfrontals, parietals, mastoid, and some of the occipital plates 

 are present : all these bones are united by sutures. The external 

 surface of the dermal plates is coarsely striated or ridged ; the ridges 

 radiate for the most part from the centre towards the margin, the 

 surface being covered by strips of ganoine. The orbit is oval. The 

 base of the skull is formed by bones more completely ossified than 

 in the existing Sturgeons : these are more extensive than in the 

 Teleostean fishes, being the equivalents of the sphenoid bones of the 

 latter. Sir P. Egerton, in his description of the genus Chondrosteus, 

 states that the elements of the scapular arch, which in recent 

 Sturgeons are three in number, are reduced to two in the fossil 

 genus by the coalescence of the scapula and the coracoid. The 

 author describes it as composed of a series of three bones, supra- 

 scapula, scapula, and coracoid (or clavicula). The last is united 

 with the pectoral fin by two bones, apparently representing the 

 radius and nlna of Owen (coracoid and scapula of Parker). The 

 pectoral fin is large and comprised forty-two rays. The mandibles 

 and maxillaries are large and well ossified, in this respect differing 



