10 MR. G. A. BOULENGEE ON LIZAEDS 



supraocular), partly on the side, thus combining the two extreme positions met with 

 in L. viiiralis and allies, which Mehely explains as due to the shields not being 

 homologous. 1 regard them as certainly homologous : if lateral in position, they have 

 been reduced in width and pushed aside by the greater lateral extension of the 

 parietals ; if dorsal, the lower portion has disappeared through disintegration. Mehely 

 would agree, I should think, that either case must be a reduction I'rom the condition 

 in L. agilis. Mehely's interj^^i-etation answers better in the case of the lizards of 

 the Section Gallotia. It seems that the anterior temporal shield, which conforms to 

 the L. agilis-ocellata type in L. stehlini and L. simonyi, has in the other species 

 actually fused with the parietal shield, a view which is supported by the fact that, 

 occasionally, in L. galloti, a short cleft is present in the parietal, exactly in the 

 position which the suture between the two shields would occupy, and explains why, 

 in this species, unlike most others, the last upper temporal is large as compared to 

 those preceding it. 



I conceive five to be the original number of shields on the upper lip to below 

 the eye, the fifth being the subocular. This subocular becomes more and more 

 differentiated from the labials pro[)er by narrowing inferiorly, and may ultimately be 

 excluded from the labial border, as in some Eremias and Acanthodadylus. In 

 L. agilis this shield is very variable in shape, and is usually preceded by tour upper 

 labials. Five or six anterior upper labials become normal in several iorms of 

 the L. galloti and muralis groups, and the number is often reduced to three 

 in the L. vivijmra group. As a general rule, the number of labials increases with 

 the length of the snout. 



5. The lower eyelid is opaque, usually with more or less enlarged scales in the 

 middle, in all species of Lacerta but one, L. ijerspicillata. In L. parva, danfordii, 

 and ditgesii these large scales have a tendency to become translucent. But in 

 L. perspicillata a perfectly transparent disk, formed of a single large scale, occupies 

 the centre of tlie lid. We know of no connecting-links in the genus Lacerta leading 

 to this remarkable feature, but we can realize the process of ioimation of the disk 

 by examples drawn from the genera Lataatia and Eremiaa, in which we tind a varying 

 number (2 or more) of central scales becoming enlarged and transparent, and by their 

 fusion realising the condition in L. perspicillata. In Cahrita the transparent disk is 

 very large, occupying nearly the whole of the lower eyelid, and, a step further, in 

 OjiJiiojJS, the lower eyelid has lost its mobility and fused with the upper, such Lizards 

 having been regarded as deprived of eyelids. 



6. A denticulation formed by projecting, more or less pointed scales in front of the 

 ear-opening is known in a single species oi Lacerta, L. atlantica, but I find a slight 

 indication of it in some specimens of L. viuralis, var. campedris, and in L. jayakuri. 

 The character is further developed and reaches its highest degree in species of 

 Acanthodadylus. 



