FUNDAMENTAL RELATIONS OF ANIMALS 49 



Many more examples might be quoted, were our knowledge of 

 the geographical distribution of the lower animals more precise. But 

 these will suffice to show that whether high or low, aquatic or ter- 

 restrial, there are types of animals remarkable for their peculiar 

 structure which are circumscribed within definite limits, and this 

 localization of special structures is a striking confirmation of the 

 view expressed already in another connection, that the organization 

 of animals, whatever it is, may be adapted to various and identical 

 conditions of existence, and can in no way be considered as origi- 

 nating from these conditions. 



SECTION XII 



SERIAL CONNECTION IN THE STRUCTURE OF ANIMALS WIDELY 

 SCATTERED UPON THE SURFACE OF OUR GLOBE 



Ever since I have become acquainted with the reptiles inhabiting 

 different parts of the world, I have been struck with a remarkable 

 fact, not yet noticed by naturalists, as far as I know, and of which 

 no other class exhibits such striking examples. This fact is that among 

 Saurians, as well as among Batrachians, there are families, the rep- 

 resentatives of which, though scattered all over the globe, form the 

 most natural connected series, in which every link represents one 

 particular degree of development. The Scincoids,^^ among Saurians, 

 are one of these families. It contains about one hundred species, re- 

 ferred by Dumeril and Bibron to thirty-one genera, which, in the 

 development of their organs of locomotion, exhibit most remark- 

 able combinations, illustrated in a diagram, on the following page[s]. 



Fully to appreciate the meaning of this diagram, it ought to be 

 remembered that the animals belonging to this family are considered 

 here in two different points of view. In the first place, their zoolog- 

 ical relations to one another are expressed by the various combina- 

 tions of the structure of their legs; some having four legs, and these 

 are the most numerous, others only two legs, which are always the 

 hind legs, and others still no legs at all. Again these legs may have 



^ For the characters of the family see Andr^ M. C. Dumeril et G. Bibron, Erpetolo- 

 gie generate ... (9 vols., Paris, 1834-1854), V, 511. 



