196 Annals of the South African Museum. 



what is now the Palaearctic Region differed strongly from that of 

 the present day. Iguanidae, now confined to the New World, 

 Fiji, and Madagascar, occurred in the Miocene of Europe, and the 

 Pleurodirau Chelouiaus, at the present time found only in Tropical 

 and South Africa, Madagascar, and South America, were represented 

 in the Eocene as far north as England. Wilhin the last fifteen years 

 the range of Nucras has been ascertained to extend further to the 

 north in Africa (Lake Victoria), and, in accordance with the view of 

 the probable origin of these lizards, the northernmost species 

 (N. emini) has every claim to be considered, from the morphological 

 standpoint, as the most primitive of the genus. I therefore believe 

 that Nucras had a northern origin, an opinion further supported by 

 the fact that the Lacertidae, like the Agamidae, being absent from 

 Madagascar, must have extended their range towards the south only 

 after the connection of Africa with that island had been severed, 

 whilst the presence of Iguanidae, Grerrhonotidae, and Chamaeleontidae 

 may be explained by these having reached Madagascar from Africa at 

 a period previous to the southern extension of the Lacertidae and 

 Agamidae. 



The reasons for regarding the genus Nucras as the most primitive 

 of the Lacertidae are the same as set forth in my recent paper on the 

 derivation of the species of Lacerta,* in which L. acjilis is held to be 

 the surviving representative of the ancestor of most, if not all, of the 

 species of the genus Lacerta with which we are at present acquainted. 

 Of the ten characters, or sets of characters, there mentioned nine are 

 in accoi'dance with this view, the only two (7, 9) in which Nucras 

 is not so primitive being the reduction of the dorsal lepidosis to 

 smooth granules and the long tail, in which all the species at present 

 known agree. f Otherwise we find (1) constant presence of teeth on 

 the palate ; (2) a non-depressed or feebly depressed skull of moderate 

 ossification (no supraorbital fontauelle, no dermal ossifications in the 

 temporal region), although less primitive than that of L. agilis, owing 

 to the narrower internarial space (comparable to L. vivipara in 

 N. delalandii, to L. muralit in N. tessellata) ; (3) presence, in some 

 forms at least, of the foramen parietale ; (4) nostril between two or 

 three nasals, the first upper labial being well separated from it, and 

 absence, in some species, of small scales between the supraoculars and 

 the superciliaries ; (5) lower eyelid without transparent disc ; (6) no 



* Tr. Zool. Soc. xxi., 1916, p. 1. 



t Unless it be true that the tail of N. loulengeri is only 1? to li times the 

 length of head and body, as stated in the description ; but it is not improbable 

 that the fact of the organ being in a regenerated condition has been overlooked. 



