42 Mr. G. A. Boulenger — '' Zur Losung 



great importance to tlie size and position of the true supra- 

 orbital bone, and yet a skull of an adult male of the var. 

 Bedriagce which I have prepared for the purpose of verifying 

 his statements has the supraorbital bone entirely concealed 

 under the first osteodermal supraocular and the first supra- 

 ciliary, and this bone is rather smaller tiian in a male of the 

 var. tiliguerta from Cagliari. It is clear to 

 me that Prof. v. Mdhely is not familiar with 

 the skull of the true L. tiliguerta, which, as 

 stated above, he regards as pyramido- 

 cephalous. The sketch here given of the 

 bony plates of the supraocular region, care- 

 fully prepared for me by Mr. E. Degen 

 from an adult male from Cagliari, shows that 

 the ossification of that region may in indi- 

 vidual cases be incomplete ; and I should 

 add that the nasal apertures may be nearly 

 as large as in Z. Bedriagce^ also that ossifi- 

 cations are altogether absent from the 

 temporal region. I have already pointed Supraocular region 

 out*, and still believe, that the var. ^^ L. tihguerta. 

 tiliguerta constitutes in a certain sense a 

 link between the var. Brueggemanni on the one hand, and 

 the vars. Bedriaga^. and sardoa on the other. 



Mr. Degen has also found the supraocular region incom- 

 pletely ossified in male specimens of the vars. Lilfordi and 

 Jiumana. 



Prof. V. Mehely thinks a study of the cranial characters 

 affords a key to the solution of the L. muralis problem from 

 the point of view of the phylogeny. He starts from the 

 assumption that the more feeble development of the osteo- 

 dermal plates of the head indicates a lower stage of evolution, 

 and as the ultra-platycephalous forms of wall-lizards belong 

 more to the reticulate type of pattern, whilst the striated 

 lizards (with six light streaks) are pyramidocephalous, he 

 declares " so ist es klar, dass die liiingsstreit'ung nicht die 

 phyletische Ausgangsform kennzeichnet, wie Eimer annahm, 

 sondern gerade die phyletische Eadstufe anzeigt." 



I wish to give here my reasons for differing from this view. 

 In most groups of lower vertebrates, in which we have some 

 indication of orthogenetic derivation of forms, we find that a 

 massive skull degenerates into a more feebly ossified one 

 so far as the " roof " is concerned. Among Silurid fishes we 

 have a beautiful example in the series Clarias — Allabenchelgs 



* L. c. p. 404. 



