NOTES ON THE FAUNA AND FLORA OF SARAWAK. 209 



The Snakes of Sarawak are numerous and mostly arboreal in 

 habit : a green colouration is common in a number of distinct 

 genera {e.g., the slender "whipsnake, Dryophis prasinus, the Coluber 

 oxycephala, and even the viper, Lachesis wagleri). The same 

 green colour occurs in the arboreal snakes of South Africa {CJdor- 

 ophis and Dendraspis), but these are relatively few in number of 

 species. Thoroughly aquatic snakes are represented in Sarawak 

 by a number of species of the HomalopsincB ; these are not found 

 in South Africa. It is a curious fact that those of Sarawak are 

 appreciably bigger, on the whole, than those of South Africa. 

 The large snake-eating hamadryad {Naia bungarus) of Sarawak 

 attains a length of as much as 15 feet and must be considered 

 the most poisonous snake in the world, whereas the largest cobra 

 of South Africa {Naia nigricollis) does not reach more than half 

 that length : the Sarawak Python (P. reticulatus) may grow to a 

 length of 30 feet, but the Python sebce of South Africa does not, I 

 believe, exceed 20 feet. Burrowing snakes, the various species of 

 Typhlops and Glaucoma, are fairly common here : in Sarawak 

 Glaucoma is absent and Typhlopid?e are rare, though the burrowing 

 habit is found in two much larger snakes {Cylindrophis rufus and 

 C. Uneatus) belonging to a different family, the Ilysiidae. It is 

 recorded on good authority that one of the Bornean snakes (a 

 Chrysopelea) has the flying habit, the ventral scutes of its body 

 being modified accordingly. 



In the Batrachia also the arboreal habit has impressed itself, 

 and Wallace long ago published an account of the flying frog of 

 Borneo. These flying frogs (several species of Rhacophonis), 

 which have a very widely extended web between the digits of 

 the hand^ and feet, are in reality very closely allied to the common 

 frogs of the genu> Rana, so abundant in South Africa. Some of 

 the Sarawak frogs have rather peculiar breeding habits : there are 

 two species {Calophrynus pleurostigma and Ixalus petersii) which 

 habitually deposit their eggs within the pitcher of a Nepenthes, 

 and in the pitcher fluid, where also the giant mosquitoes of the 

 genus Toxorhynchites (near Megarhinus) and various other Diptera 

 inva iably lay their eggs, the whole of the larval history of the 

 irog is pas-.ed. We are quite prepared to find tha' some of the 

 South African frogs have unusual breeding habits or abbreviated 

 life histories, but very little appears to be known on this subject. 



In the groups of freshwater fishes the Sarawak and South African 

 faunas have much in common, though Sarawak is very much richer 

 in genera and in species. The special abundance of the Bornean 

 fish fauna is not to be regarded simply as a consequence of the 

 strong development of extensive water courses covering the whole 

 area of that large island, for it should be noted that the adjacent 

 islands of New Guinea and Celebes, which have also good river 

 systems, have a scanty fish fauna. The Cyprinina and various 

 group cf the Siluridae {Clariina, Silurina and Ariina) abound in 

 the rivers of Borneo : whilst in South Africa the Cyprinid genera 

 Barbus and Labeo and the Siluroid genus Clarias — which three 

 genera all occur in Sarawak — include some of the commonest of 

 freshwater fish. The Labyrinthici, a family whose members have 



