98 A NATURALIST IN BORNEO 



to be inconvenienced in the slightest degree thereby, 

 he believes that the fish-spines are eliminated from the 

 body of the snakes by passing simply through the wall 

 of the alimentary canal and through the body-wall to 

 the exterior. It is difficult to see how the spines of 

 such a fish as Chorinemus toloo could pass out of the 

 snake's body in any other way. The same naturalist 

 confirms an observation that I have made more than 

 once, that Sea-Snakes, when irritated, do not hiss but 

 utter a low gurgling noise. 



It is of interest to find that in each of the three 

 sections of Colubridce there is one sub-family of aquatic 

 snakes. In the section Aglypha we have the Acrochord- 

 ince, powerful crushing snakes, living in the sea near 

 the shore and in rivers ; in the section Opisthoglypha 

 we have the Homolopsince, some species of which are 

 commonly found in mud on the banks of rivers, others 

 in the rivers themselves, others on the sea-shore ; and 

 in the section Proteroglypha, the Hydrophiince, which in 

 their structure are far better adapted to an essentially 

 marine life than either of the other two sub-families. 



This short and incomplete review of the snakes of 

 Sarawak may conclude with some remarks on their 

 coloration and its significance. We have seen that 

 certain poisonous snakes, the Vipers, as well as certain 

 non-poisonous snakes, are coloured in harmony with 

 their surroundings. This resemblance of animals to 

 inanimate surroundings is a very common phenomenon 

 in Nature, and in the case of plant-eating defenceless 

 creatures has a protective purpose and is termed "pro- 

 tective resemblance." In the case of snakes, animals 

 which prey on other animals, this resemblance plays a 

 double role, for it enables the snakes to escape not 



