THE LIMBS OF LIZARDS 135 



may be non-existent. We may represent the origin 

 of the limbless lizard on this view thus : — 



TMale (long limbs) Covariation 

 rMale (long limbs) loffspj-jjig J Female (long limbs) J 

 iFemale (long limbs)/ | Female (short limbs), a spontaneous 



1^ variation conferring an advantage. 



If a similar variation arose in a male of the same 

 or another litter, and the two spontaneous variations 

 paired, the result would be — 



Male (short limbs) \ og-g j ^ short-limbed family, a new species. 

 Female (short limbs)/ ^ ^ J^ f 



And similarly with other variations of kind or degree. 



This brief outline of the two main biological views 

 on this subject is merely intended to direct the 

 attention of the field-naturalist reader to the explana- 

 tions offered by science to account for the origin of 

 such an anomalous reptile as the slow-worm is, as well 

 as for the origin of species in general. It merely 

 touches the fringe of the greatest of all biological 

 subjects, and of necessity ignores all the numerous 

 sidelights which may be thrown upon it ; but it is 

 hoped that it may be just sufficient to induce readers 

 to examine the matter for themselves, and apply what 

 they learn to the species of animals in their own 

 country. 



It remains to be noted what degrees of variation in 

 the matter of limbs are to be found existing at the 

 present day amongst lizards, which may be regarded 

 as connecting links between the ordinary four-limbed 



