154 A. INGRAM AND J. W. S. MACFIE. 



The leaves of P. stratiotes have an unwettable surface and are strongly ribbed on 

 the underside, so that as the plant expands the outer leaves come in contact with the 

 surface of the water and carry down with them a film of air. It was to the under- 

 surface of these outer leaves that the larvae of M. splendens attached themselves, 

 lying horizontally with their siphons inserted into the film of air, and in maintaining 

 this position the hooks described above were no doubt of great assistance. In this 

 manner they were able to live for a long time (in one experiment 24 hours) without 

 direct access to the air and may moult whilst still submerged. 



Chaoborus ceratopogones, Theo. 



The head is small and laterally compressed, as compared with the head of a larva 

 of the Culicinae, and carries very few hairs. Two delicate tufts of simple hairs are 

 visible, one in front of and one behind the prominent eye. The mouth-parts de- 

 scribed by Miall (" Aquatic Insects " pp. 116-117) are very well seen in the larval pelt. 

 There is a distinct neck. 



No plumes are present on the thorax, but on its lateral aspect short tufts of simple 

 hairs occur and dorsal to these hair-tufts a single longer hair. 



The abdominal segments have laterally a single long hair and a tuft of simple hairs 

 ventral to this hair similar to the arrangement of the lateral hairs on the thorax. 

 The usual paired and pigmented air sacs are present in the thorax and the seventh 

 abdominal segment. The ventral brush on the ninth segment is composed of 

 about 20 curved and elegantly plumose hairs. The anal papillae are short, the 

 ventral pair being slightly longer than the dorsal. The hairs on the dorsal extremity 

 of the ninth segment are one above and one below ; they are nearly equal in length 

 and are strongly plumose. 



