ii4 REPTILES 



On the other hand, the amphisbaenas {AmphisbccnidceX so 

 called from the similarity of the head to the tail and the pos- 

 session of the power of going equally well either backwards or 

 forwards, are purely burrowing lizards, with a remarkably 

 worm-like appearance, the body being divided into numerous 

 rings or segments, each divided into a number of squares re- 

 presenting aborted scales ; functional scales being restricted to 

 the head, with the exception of the members of the genus Chirotes, 

 in which there are short four-clawed front-limbs, amphisbaenas 

 are completely worm-like lizards, although they retain vestiges 

 of the bones of the shoulder and pelvic girdles, those of the 

 former being the more reduced. Amphisbaenas, which fre- 

 quently infest ants' nests and manure-heaps in tropical countries, 

 progress in a different manner to snakes and other snake-like 

 lizards, the body being thrown into vertical instead of horizontal 

 undulations ; this alone being sufficient to demonstrate their in- 

 dependent origin from some extinct four-limbed stock. The 

 numerous species of the typical genus A mphisbcena are restricted 

 to tropical America and Africa ; but Blanus cinereus, a pinkish, 

 grey-flecked species, is common to Spain, Portugal and 

 Morocco. 



As already stated, in all these reptiles the eye is more or 

 less degenerate ; and in describing the structure of this organ 

 in the amphisbaenan known as RJiineura florida, Professor 

 C. H. Eigenmann refers to the occurrence of a fossil representa- 

 tive of the same genus in the Miocene of Dakota. Nothing is 

 known with regard to the eyes of the extinct form, but from 

 the fact that all the living members of the group are blind, it 

 seems practically certain that the degeneration of the eyes took 

 place before the differentiation of the existing genera, in other 

 words, at least as early as the Lower Miocene. In the existing 

 form not only is the eye invisible externally, but there is no 

 indication of the aperture by which it formerly opened on the 

 surface. 



Yet another independently evolved group of snake-like 

 lizards is represented by the half-score or dozen species of the 

 Australasian family Pygopodidce, in which vestiges of the hind- 

 limbs are retained in the form of scaly fin-like flaps ; these fre- 

 quently showing distinct remnants of the five toes. In 

 Pygopus itself, as typified by P. lepidopus, the limb-flaps are of 



