164 Lacertidn'. 



other species diverge from it. P. JiiKpanicus differs almost exclusively 

 in the spinulose scutellation of the toes — an adaptation to the sandy 

 localities it frequents — and in the absence of vertically enlarged scales 

 on the lower eyelid. P. microdacti/lus has developed a peculiar sub- 

 digital scutellation, very diffei'ent from that of P. Idspanicns, but yet 

 approaching the pristidactyle condition, as first pointed out by 

 Bedriaga, and the lower eyelid is as in P. hispanicus ,- both these 

 species may have been evolved out of P. blanci. And lastly, P. algirus 

 has acquired a peculiar ventral lepidosis, highly aberrant for the 

 family Lacertidse, but which must be regarded as derived from the 

 normal condition ; its subdigital scutellation is iu an unstable con- 

 dition, sometimes identical with that shown by P. blanci, sometimes 

 nearly realizing the true pristidactyle type ; in the presence of teeth 

 on the pterygoid bones it is more primitive than the three other species 

 of the genus, from any of which it cannot therefore be derived. 



Synopsis of the Species. 

 I. Ventral plates of unequal width and moderately overlapping, the 

 largest much broader than long ; granular scales on sides of 

 neck ; no teeth on the palate ; 9 to 15 femoral pores on each side. 

 Collar distinguishable ; 27 to 32 scales round the body, ventral 

 plates included ; lower eyelid with vertically enlarged scales 

 in the middle ; subdigital lamellae tubercular, 17 to 21 under 

 the fourth toe ....... P. blanci, Lataste, p. 164. 



Collar distinguishable ; 30 to 42 scales round the body ; lower 

 eyelid without vertically enlarged scales ; subdigital lamellae 

 sharply keeled, 16 to 23 under the fovu-th toe P. hispanicus, Fitz., p. 167. 

 No collar ; 27 to 30 scales round the body ; lower eyelid 

 without vertically enlarged scales ; subdigital lamellae with 

 strong, obtusely keeled tubercles, 15 to 17 under the fourth 

 toe ....... P. microdactylus, Boettg., p. 173. 



II. Ventral plates subequal, rounded or obtusely pointed behind, 

 strongly overlapping ; no collar ; strongly imbricate, keeled 

 scales on sides of neck ; pterygoid teeth -, 30 to 34 scales 

 round the body ; subdigital lamellae smooth, tubercular, or 

 feebly keeled, 19 tn 24 under the fourth toe ; 13 to 21 

 femoral pores on each side, usually 15 to IS . P. alginis, L., p. 175. 



1. PSAMMODROMUS BLANCI. 



Zerzoumia blanci, Lataste, Le Natural. 1880, p. 299; Bedriaga, 

 Abh. Senck. Ges. xiv, 1886, p. 411. 



Algira (Zerzumia) blanci, Boettg. Abh. Senck. Ges. xiii, 1883, 

 p. 116. 



Psaminodromus blanci, Bouleng. Cat. Liz. iii, p. 48 (1887), and 

 Tr. Zool. Soc. xiii, 1891, p. 127, pi. xiv, fig. 2 ; Werner, Verh. Zool.- 



