13 



hairs, and a similar pair halfway down, and the rings of a third pair at 

 the base but no hairs. Each epicranial plate bears a pair of pigment 

 eye-spots placed antero-laterally ; they are surrounded by a few hairs 

 of medium length. Two long hairs arise on each side of the head and 

 some short ones near the eye-spots, and on the ventral surface of the 

 epicranial plate. Some species of the " Pusio " group can withdraw 

 their heads partly into segment I. and then the posterior hairs are not 

 present or are very small, but the pits and chitinous rings can generally 

 be seen. 



The position of the eyes varies in different species, and in two 

 species (Nos. 13 and 14 of Appendix) the eyes are fused into one. 



On the ventral surface great variations are found in the shape of 

 the bay, and the density of the chitin, in some species portions being 

 quite black. The free edge of the bay is slightly thickened, otherwise 

 the epicranial plates and also the clypeus are of a uniform density. This 

 is true of all the larvae I have examined belonging to the "Pusio" 

 group, but not so in other species. In larva No. 7 a large area 

 surrounding the bay and reaching to the striated flaps is black with 

 chilin ; and in larva No. 14 half the ventral surface is thus chitinized, 

 while in larva No. 15 the bay is divided into an anterior and posterior 

 part united by a narrow isthmus. A slight groove separates off a small 

 anterior portion of the epicranial plate, which rises upwards and projects 

 slightly beyond the rest of the plate as a kind of boss from which the 

 antenna arises. A similar boss is seen in Anopheles* but the most 

 remarkable extension of this prominence is seen in LAUTERBORN'S 

 Larva III., belonging to the " Pusio " group, while in my larva No. 5 

 the prominence is of considerable size, extending as far forward as the 

 extended labrum. 



The antennae are very highly developed. Each is composed of a The Antenna:. 

 long basal segment, curving outwards and downwards ; this bears near 

 the proximal end a small chitinous ring (sensory spot) without a hair, 

 and a third of the way up the segment there is another smaller ring 

 with a long chitinous hair attached, This segment is moved by strong 

 muscles and is capable of slight retraction beneath the boss. Other 



* Anopheles, by NUTTALL & SHIPLEY, Journal of Hygiene, vol. I., No. I. 



