8 Lacertidse. 



mind that, in Tertiary times, the general character of the reptile 

 fauna of the northern parts of what is now the Palseartic Eegion 

 differed very strongly from that of the present day. IguanidsB, now 

 confined to the New World, Fiji, and Madagascar, occurred in the 

 Miocene of Europe, and the Pelomedusid Chelonians, 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. 

 Within 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 (JV. 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 Lacertidse, like the 

 Agamidse, being absent from Madagascar, must have extended their 

 range towards the south after the connexion of Africa with that 

 island had been severed, whilst the presence of Iguanidse, Gerrhono- 

 tidae aiid Chamseleontidae may be explained by these having reached 

 Madagascar from Africa at a period previous to the southern extension 

 of the Lacertidse and Agamidse. 



The reasons for regarding the genus Nucras as the most primitive 

 of the Lacertidse are the same as set forth in my remarks on the 

 derivation of the species of Lacerta (p. 29), in which L. agilis 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 10 characters, or sets of characters, there men- 

 tioned, 8 are in accordance with this view, the only two (7, 9) pointing 

 to Nucras as 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. 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. inuralis in N. tessellata) ; (3) presence, in some forms, 

 at least, of the foramen paiietale ; (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 



* Unless it be true that the tail of N. boulengeri is only IJ to 1^ times the 

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

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

 overlooked. 



