'236 SPOLIA ZBYLANICA. 



but non-vascular ; this membrane, which I take to be the epidermal 

 tract of the outer iimnion, couBists of a pavement-epithelium in 

 which the cell-boundaries, vesicular nuclei and nucleoli are clearly 

 visible without staining ; (3) a thicker, though still transparent, 

 vascular allantoic membrane traversed by blood-vessels which 

 give rise to dense capillary networks over the surface of the egg. 



From the above description it is evident that, from a reptilian 

 standpoint, the viviparity of Cuijhotis is very complete. In this 

 connection it may be noted that the wall of the oviduct is also 

 well-supplied with blood-vessels, a large trunk proceeding along 

 the mesometric line. It seems almost certain that gaseous and 

 probably also liquid transfusion from parent to embryo takes place 

 through the thin intervening membranes. It is not always easy 

 to suggest an explanation for the exceptional occurrence of 

 viviparity in groups of normally oviparous animals. It seems to 

 depend upon various conditions which may react upon the 

 organism separately or in combination. Of these conditions the 

 most obvious are habits and habitat (whether arboreal, deserti- 

 colous, subterranean), temperature and moisture. There are 



Embryo of Cophotis ceylanic ; lying in a dilatation of the oviduct. The 

 dotted portion indicates the yolk. At each side of the figure is the cut end 

 of the oviduct. 



several parallel examples which may help to throw light on this 

 subject. Cophotis is arboreal as shown bionomically by its actual 

 occurrence as well as structurally by its prehensile tail, but less so 

 than the Chameleon which has modified hands and feet in addition 

 to its prehensile tail. Nevertheless most Chameleons lay eggs, an 

 exception being afforded by Chameleon pumilus, the Dwarf 

 Chameleon of South Africa which is ovoviviparous. This species 

 is described by Dr. Gadow (Cambridge Nat. Hist. Amphibia and 

 Reptiles, 1901, p. 580) as "relatively hardy, being as a native of 

 South Africa, accustomed to cold nights." In this respect it offers 

 an analogy to Cophotis ceylanica, which has almost exactly the 

 same size as the South African Chameleon, namely, 5-6 inches, 

 and is accustomed to the cold nights of the upper montane zone 

 of Ceylon. 



