1903 Reptile Studies 307 



Museum Catalogue, G. A. Boulenger). Another member of 

 the slow-worm family (Ophisaurus opus) possesses external 

 rudiments of hind-limbs. This last species is of interest 

 because the shape, arrangement, and number of the head 

 shields are extremely similar to those of the slow- worm. 

 It is known as the glass snake, and is found in South- 

 Eastern Europe, South-Western Asia, and North Africa, 

 growing to a length of 3 feet. Finally, in this connection 

 may be mentioned the genus Chamczsaura, a South African 

 genus, with three species which exhibit a curiously progressive 

 diminution in the limbs which may be thus summarised : — 



1. C. tunc a. — Both pairs of limbs present, pcntadactyle. 



2. C. auguina. — Both pairs of limbs present, reduced to 

 stumps (styliform and undivided). 



3. C. macrolcpis. — Fore-limbs absent; hind-limbs styli- 

 form, undivided. 



A more gradual and complete reduction is seen if the 

 whole of the genera in the slow-worm family be compared. 

 Thus : — 



Synopsis of the Genera in the Anguid/e. 



1. GcrrJionotus. — Limbs four, pentadactyle. 



2. Ophisauncs. — Limbs absent, or hind pair rudimentary 

 externally. 



3. Diploglossus. — Limbs four, pentadactyle. 



4. Saurcsia. — Limbs four, tetradactyle. 



5. Panolopus. — Limbs four, monodactyle or didactyle. 



6. Opliiodcs. — External rudiments of the hind-limbs 

 only. 



7. Angu is. — No trace of limbs externally. 



Here we have in the one family a number of genera 

 exhibiting a series of variations, from the four-limbed five- 

 fingered type to the highly specialised scrpentiform creature 

 without any external limbs at all, as in the slow-worm. 

 It is the existence of so many intermediate conditions of 

 organs that prove animals to be connected by almost every 

 possible structural modification, and which makes it im- 

 possible to believe that species could have arisen except by 

 a gradual transition of forms from the generalised type to 



