Scientific Intelligence. — Zoology. 447 



conditions favourable, or otherwise, to existence, and conse- 

 quently to development. Proceeding on these principles, it is 

 easy to perceive that the limits of variation in the different 

 pieces of a skeleton are much wider than was at first supposed. 

 This fact is confirmed by daily observation, and becomes more 

 and more obvious in proportion as our osteological collections 

 extend, and are made more complete. The consequence is, 

 that affirmations in reference to palaeontology ought to be 

 made in a less decisive manner, and they will thus become 

 more exact, by resting on a more rational investigation. 

 Then, by taking into consideration the conditions derived from 

 the natural history of living animals, we may perceive that 

 certain of them, not to say all, when we have respect to the 

 harmony of creation, may be influenced more or less, in con- 

 sequence of the material and intellectual development of man, 

 to such a degree, that some have disappeared during the his- 

 torical period, and almost from under our eyes, from certain 

 countries, and even from the surface of the earth, as has taken 

 place with the dronte, or the dodo, in the class of birds." 



M. Jules de Christol is, perhaps, one of the first palaeontolo- 

 gists who has studied the subject in this light. He has shewn, 

 many years ago, that the fossil bones on which G. Cuvier es- 

 tablished his Hippopotame moyen, did not belong to a hippo- 

 potamus, but rather to an animal of the genus lamantin, or 

 dugongs, which likewise live, it is true, in water, and are her- 

 bivorous, but do not belong to the same natural family. M. 

 de Christol's new memoir may be said to be a continuation of 

 that of which we have already spoken, and still refers to the 

 correction of an error which escaped G. Cuvier, respecting bones 

 ascribed by him to a species of seals, carnivorous marine ani- 

 mals, and which M. de Christol supposes likewise to be those 

 of a dugong. We shall not revert to what has been already 

 said on this subject. We shall only add the following re- 

 marks with which M. de Blainville concludes his report. 



" M. de Christol's researches give prominence to this fact, 

 among others, that at times more or less remote from the pre- 

 sent, all the gulfs of Europe into which large rivers discharge 

 their waters, produced a more or less distinct species of this 

 family (the dugongs) j as there is still found one in countries 



