80 



MR. E. G. BOULENGER ON SOME 



however, a very distinct species, quite different from the nume- 

 rous forms of G. ocellatus *. In its shorter not so unequal toes, in 

 its large ear-opening, and in its long, thick tail, it approaches the 

 groups including C. lineatus, tridaciylus, guenthein ] and my 

 father has given it as his opinion, that, although derived from the 

 same stock as C. ocellatus, it represents one of the pentadactyle 

 forms from which the more degenerate types referred to above 

 have been evolved ; whilst a continuous d-egeneration can be traced 

 i'rom C. ocellatus through C. sepoicles to C. delislii and C. mauri- 

 tanicus. 



In all, therefore, we now have, apart from the typical form, 

 seven varieties of the lizard C. ocellatus, and it is interesting 

 from the evolutionary point of view that they are geographically 

 connected, it being possible to trace every link in the chain from 

 the short and stout variety with as many as 40 scales from 

 Morocco, which must be regarded as the most generalized form, 

 to the long and slender type with only 22 scales round the body 

 from Abyssinia and Somaliland. 



The general reduction in the number of scales takes place 

 as follows : — 



1. var. 2)olylepis (34-40 scales). 



occidentalis (30-32 



vittatus 

 tiligugu 



(30-34 

 (28-34 



5. forma typica (26-32 



6. var. linosce 



7. ,, ragazzii 



8. ,, hottegi 



m 



(24 



(22-24 



Morocco. 



I. of Fuertaventura. 

 Tangier. 



Sardinia, Sicily, Malta, 

 S. Italy, Algeria and 

 Tunisia , N. of the Sahara. 



Arabia, Persia, Egypt to 

 Algerian Sahara, Syria, 

 Cyprus, Greece, Eritrea. 



I. of Linosa. 



Assab. 



Abyssinia, Somaliland. 



The following are definitions of the 8 forms into which 

 C. ocellatus may be divided : — 



1. Tar. polylepis Blgr. 34-40 scales round the body, the two 



median dorsal row^s not enlarged ; light brown above, with- 

 out ocelli, but with a round yellowish spot on each scale, 

 forming regular longitudinal series sometimes separated by 

 dark lines : young with vertical black-and-white bars on the 

 sides of the neck. Maximum length from snout to vent 

 155 mm. 



2. Var. occidentalis Stdr. 30-32 scales round the body, the two 



median dorsal rows not enlarged ; coloration as in the 

 preceding, but the yellow spots less numerous. Maximum 

 length from snout to vent 100 mm. 



* Ch. hottegi var. thierryi Tovnier, Arch. f. Nat. 1901, p. 87. 

 Ch. thierryi O. Neumaiii], Zool. Jahrb., Syst. xxii, 1905, p. 401. 

 Ch. pulchellus Mocquard, Bull. Mus. 1906, p. 466. 



