PROCEEDINGS OP SOCIETIES. 273 



This rod-like finger formed the framework which supported a membranous 

 wing, by which this wonderful creature was enabled to fly in pursuit of the 

 myriads of insects that fed on the honeyed nectar of the flora of the ancient land. 

 In concluding his description of this family, he remarked that their structure 

 formed the passage, in a most remarkable manner, from the low organization of 

 the cold-blooded Vertebrata to the more complicated mechanism of birds and 

 Mammalia ; and that the peculiarities of structure, by which these creatures 

 were linked with them, were neither few, nor difficult to demonstrate ; these the 

 lecturer pointed out in a most satisfactory manner, by reference to numerous 

 anatomical specimens and diagrams. He next proceeded to the consideration of 

 Fossil Crocodiles, and dwelt upon the curious fact first observed by Cuvier, and 

 confirmed by subsequent discoveries, that the fossil Crocodilidce, found in the 

 saliferous, oolitic, and cretaceous systems, were allied to our modern long-nosed 

 Gavials, whilst those found above the chalk approached the broad-muzzled Alli- 

 gators and Crocodiles. The lecturer drew some interesting inferences from these 

 facts regarding the character of the animals, on the too rapid increase of which 

 these fossil Crocodiles were destined to keep a vigilant check. In reviewing the 

 history of the reptile age, Mr. W. gave some satisfactory physiological reasons for 

 supposing that the arctic land, during those periods of the earth's history, enjoyed 

 a much higher temperature than it does now. The history of fossil fishes was 

 next introduced, and the lecturer remarked that this branch of Paloeontology was 

 rapidly advancing through the zeal and industry of Professor Agassiz, the great 

 master of this department of Fossil Zoology. He described the condition in 

 which the remains of the finny tribes were found, and the localities in 

 which they occur ; and the interesting facts which had been revealed by Agassiz' 

 labours, that none of the many hundreds of genera now existing are found in any 

 formation older than the chalk ; that in the upper members of this system there 

 are among the many extinct genera only five which are now living ; that of the 

 fossil fishes, discovered in the older tertiary strata, one half belong to existing 

 genera, the other half to kinds that are now unknown. These discoveries har- 

 monize in the most interesting manner with similar results obtained from an 

 investigation of fossil reptiles and Mammalia ; and show, in a satisfactory man- 

 ner, the close affinities which exist between the tertiary period and the existing 

 order of Nature. The lecturer then explained the peculiar features of that 

 learned naturalist's classification, and showed how intimately the scaly covering 

 of fishes is related to the other parts of their economy, and how peculiarly 

 adapted his views are to the advancement of Fossil Ichthyology; seeing that, in 

 a vast number of instances, it is the scaly covering of these animals alone that 

 has resisted the rude destroying hand of time. He detailed, from specimens and 

 diagrams, the character of the fishes found in the different formations, from which 



