in the Indian Maseum, Cahutta. 31 



Var. nov. lionotum. 

 ^liiller, in pointing out that Ptychozoon Ilorsfieldu was 

 really a good species, gave as one of the diagnostic characters 

 of P. homcdocephaluni tliat there are enlarged tubercles 

 among the scales of the back. Bouleuger has recorded a 

 speciiuen, obtained in Pegu by the late Signor Fea, which 

 agrees with the latter species in the more important specific 

 characters, but lacks these enlarged tubercles. Along with 

 several typical specimens of P. homalocephalum from the An- 

 danians and Nicobars we ha.ve in the ^Museum two from Pegu 

 which agree with Fea^s specimen from the same district. The 

 occurrence of three examples from Pegu agreeing thus in 

 lepidosis seems to justify the creation of a new variety for their 

 reception. P. Iiunialocephalum var. lionotum may be defined 

 as agreeing with the typical form of the species in all respects 

 except in having no enlarged tubercles among the scales of 

 the back. 



The name of the " flying " gecko enshrines a belief that 

 the loose fold of integument and muscular tissue along the 

 sides in this species has a similar function to the '' alar " 

 membrane of Draco, enabling the lizard to take long leaps 

 through the air, and supporting it in that element. That 

 Ptijchozoon does take long leaps is very possible. So do 

 Gehyra mutdata and Htmidactylus jlaviviridis — forms in which 

 there is nothing of the nature of an aeroplane. A comparison 

 of the " alar''^ membrane of Draco with the fold of soft tissue 

 in Ptychozoon shows a very important difference — the latter 

 structure has no skeletal support. Moreover, unlike the 

 membrane of the flying squirrels and phalangers and of 

 Galeopithecus, it is not fastened to the limbs, but has three 

 free edges. It is not even supported by scales below, and 

 although there are muscles at its base — that is to say, on tlie 

 side on which it is continuous with the body-wall — they do 

 not extend to the free edges. Even if they did, they could 

 hardly keep it taut witliout dirtct or indii'ect support on 

 more than one side from some rigid structure. I have never 

 seen an adult living specimen of Ptychozoon ; but a young 

 one, in which the lateral fold was perfectly developed, was 

 kept under observation by Mr. Herbert C. Robinson and 

 myself for a fortnight. We never saw it stretch out the 

 fold, which lay curved round the side so as to be practically 

 invisible. 1 have not the slightest doubt that the use of the 

 structure is not to support the lizard in the air, but to assist 

 it in concealing itself by causing it to fit better into its 

 surroundings and be less conspicuous than it would be if its 

 body cast a distinct shadow immediately bencatii it. The 



