SNAKE-LIZARDS. 131 



Some of tlie steps of this beautiful gradation, 

 by which the four long-toed and muscular limbs 

 that mark the Lizard pass away, and leave no 

 trace in the lithe cylindrical Serpent, are thus 

 graphically enumerated by Professor Bell. " From 

 the well-known family of the Scinks {Scincidce), 

 with their true legs and five-toed feet, down to 

 the Slow -worm {Anguis fragilis) and its immedi- 

 ate congeners, every possible gradation is to be 

 found in the development of the anterior and pos- 

 terior extremities. Agreeing, as they all do, in 

 the Saurian character of the structure of the head, 

 the consolidation of the bones of the cranium 

 and jaws, and the narrow and confined gape, so 

 different from those parts in the true Serpents, 

 they yet approach the latter in the comparative 

 length of the bodies, and in the gradual diminu- 

 tion and ultimate disappearance of the extremi- 

 ties. In the genus Scincus, for instance, the limbs 

 are already less robust than those of the true 

 Saurians ; the two pairs are also more distant 

 from each other, in consequence of the greater 

 comj)arative elongation of the body. There are 

 as yet five perfect toes on each foot, which, how- 

 ever, are shorter and more even in their relative 

 proportions than in the true Saurians. These 

 deviations become increased in the genus Chalci- 

 des, and still more in Seps, which has a very 

 elongated body, the limbs extremely small, and 

 the toes only four or three on each foot. In 

 Monodactylus a further reduction takes place in 

 the development of the limbs, which have dwin- 

 dled to a mere little undivided finger; they are 

 still, however, four in number ; but in the genus 

 Bipes the anterior ones have wholly disappeared. 



