NOTES ON ANOPHELES IN CEYLON. 267 



roaches, etc., put in the water ; the cast skins of the larvae and pupae 

 are also occasionally nibbled at. I have not actually caught them 

 in the act of cannibalism, though I have seen it stated that some 

 species are addicted to the habit of devouring their weaker brethren. 



The larva? as a rule lie horizontally on the surface of the water, 

 usually on the outskirt of any patch of water weed at the margin of 

 which they feed. They appear to be very ravenous creatures, the 

 whorl organs which bring food to the larvse by the current set up by 

 their rapid motion being almost incessant throughout the day, though, 

 as far as I am aware, they cease feeding at night. 



Perhaps the most remarkable thing concerning the habits of the 

 krva is its method of feeding. The head is attached to the thorax by 

 what might almost be termed an universal joint ; it is capable of being 

 turned round iu almost a complete circle. Its usual method of feeding 

 has been well described by Dr. Sambon (loc. cit.) and Mr. Austen 

 (Practitioner, Vol. LXVI., No. 3). Lying flat on the surface of the 

 water, by a sudden and extremely quick movement it revolves its head 

 until the mouth becomes uppermost, the whorl organs are then rapidly 

 expanded and retracted, or rather perhaps by a to and fro movement a 

 considerable current is produced by which the particles of food are 

 brought to the mouth ; after some time the whorl organs cease their 

 movement and the head is as rapidly turned round again. The larva 

 also fixes itself by its caudal bristles and feeds below the surface 

 amongst the weed in a more natural manner ; it is in this position that 

 the delicate hairs which are set between the antenna? are best observed. 

 The function of these hairs, it has been suggested, is to support the head 

 when it is feeding mouth upwards. In captivity the majority usually 

 lie parallel with each other round the margin of the bowl with their 

 heads all pointing to the centre. 



I am unable to say, in spite of close observation, how many times 

 ecdysis takes place in the larval stage, but 1 think not more than 

 five or six. It invariably takes place during the hottest time of 

 the day, usually between 12 p.m. and 3 p.m. A slit appears on 

 the dorsal surface of the skin out of which the larva wriggles 

 tail first. The head, thorax and tail are then colourless, the various 

 parts of the head being indistinguishable and remaining so for some 

 time. The change takes about five hours to complete from the time of 

 the rupture of the skin to the return of the head parts to the normal ; 

 the larva afterwards proceeds to eat vigorously. 



14 



