PROCEEDINGS OF 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 
