1855.] Development of Animal Life in Time. 85 



compared with those of Scomber scomhrus, Gadus ceglefinus, &c. 

 In the latter, the tail is truly homocercal, the rays of the caudal fin 

 being arranged symmetrically above and below the axis of the spinal 

 column. 



All M. Vogt's evidence, therefore, goes to show merely that a 

 heterocercal fish is heterocercal at a given period of embryonic life ; 

 and in no way affects the truly homocercal fishes. 



In the second place, it appears to have been forgotten that, as 

 M. Vogt's own excellent observations abundantly demonstrate, 

 this heterocercal state of the tail is a comparatively late one in 

 Coregonus, and that, at first, the tail is perfectly symmetrical, i.e. 

 homocercal. 



In fact, all the evidence on fish development which we possess, is 

 to the effect that Homocercality is the younger, Heterocercal ity the 

 more advanced condition : a result which is diametrically opposed 

 to that which has so long passed current, but which is in perfect 

 accordance with the ordinary laws of development ; the asymmetri- 

 cal being, as a rule, subsequent in the order of development to the 

 symmetrical. 



The speaker then concluded by observing that a careful consider- 

 ation of the facts of Palaeontology seemed to lead to these results : 



1. That there is no real parallel between the successive forms 

 assumed in the development of the life of the individual at present, 

 and those which have appeared at different epochs in the past ; and 



2. That the particular argument supposed to be deduced from 

 the heterocercal ity of the ancient fishes is based on an error, the 

 evidence from this source, if worth anything, tending in the oppo- 

 site direction. 



At the same time, while freely criticising what he considered to 

 be a fallacious doctrine, Mr. Huxley expressly disclaimed the 

 slightest intention of desiring to depreciate the brilliant services 

 which its original propounder had rendered to science. 



[T. H. H.] 



A series of specimens of Aluminium, prepared by M. St. Claire 

 Deville, in Paris, were laid upon the Library table by Dr. Hofmann. 

 These specimens consisted of a medal, with the head of the Em- 

 peror Napoleon III., two bars, a watch wheel, and a piece of 

 copper plated with Aluminium. A large piece of Tellurium, pre- 

 pared by Dr. Lowe, of Vienna, was likewise exhibited by Dr. 

 Hofmann. 



