84 REPORT — 1842. 



elusions which I had drawn from the tribe of fishes were applicable to this 

 class only, or whether the same relation existed in the other remains of the 

 animal kingdom. 



Another fact results in the most evident manner from the simple inspec- 

 tion of the specimens of these fossils which have hitherto been collected, 

 viz. that the very large majority of the species are of middle and even of 

 small size. I dwell on this circumstance because it has afforded me an op- 

 portunity of rectifying an exaggeration which has been pretty generally 

 adopted, and which consists in representing the species of ages anterior to 

 our own as being generally larger than those now existing. The idea of a 

 gigantic size has become, so to say, the necessary reflection of a tableau of 

 fossils of all the geological epochs, and nevertheless such a manner of view- 

 ing the question is quite out of the pale of truth. In fact, if it seems strange 

 to us to find in the diluvial strata of Europe, and even of the northern por- 

 tion of this continent, fossil fragments of Pachydermata very similar to those 

 now existing in the tropical regions, and differing very much from those 

 which inhabit these countries at present, it w r ould nevertheless be an exag- 

 geration to represent those fossils as vastly superior in size to the animals 

 of the same families and even of the same genera which live in our days ; 

 and even as regards the species of Pachydermata of the lower tertiary rocks, 

 it is necessary to admit that those of our time, taking all into consideration, 

 are evidently larger than the former. I do not pretend on this account to 

 deny the fact of the existence in certain fossil families of types much larger 

 in size than those of the present day, I only intend to state that these propor- 

 tions have been exaggerated, and that this disposition to exaggeration has 

 occasioned a neglect of the study of the remote relations of these types be- 

 tween each other, and with those which have preceded and those which have 

 followed them — relations which appear to me alone capable of solving this 

 enigma. It is incontestable, for instance, that the reptiles of the oolitic rocks, 

 the Ichthyosauri and the Megalosauri in particular, possessed dimensions to 

 which no type of the reptiles of our time has been found to attain; but 

 in comparing them with reptiles now existing, it must not be forgotten that 

 these gigantic reptiles lived at a time when the Mammifera did not yet exist, or 

 at least had not yet acquired the preponderance they now have; when theCeta- 

 cea and Pachydermata were as yet only projected in the plan of Nature ; when 

 the class of fishes and that of the reptiles reigned in sovereignty ; and when, 

 consequently, it is not surprising to see the Reptilia, — which, in separating from 

 the Fishes after the carboniferous formations, are examples of a real progress 

 in this series of the Vertebrata, — prepare a new progress, a movement towards 

 the class of the Mammifera and that of the Birds by the introduction of the 

 type of the Ichthyosauri, which announces in some measure the Cetacea; of the 

 type Megalosaurus, which might be considered in relation with the Pachy- 

 dermata ; and of the bird-like type of the Pterodactyli. For my part, there- 

 fore, I cannot regard simply as ordinary reptiles those types precursory of 

 analogous types which are met with at a later period in other classes; I am 

 rather inclined to view them as types prophetic of the more recent ages ; and 

 hence it is necessary to apply to their study "a different measure from that 

 which should be employed when the object is to fix the degree of analogy 

 existing between contemporary types. I might apply these same considera- 

 tions to other families, and carry them even further, if I had not already ob- 

 served elsewhere that among the fossil fishes the family of the Sauroids, of 

 which the carboniferous series contain such remarkable fragments, might be 

 viewed as announcing, by its ambiguous characters, the introduction of the 

 reptiles, at a period when this class was not yet represented on the earth. Nor 



