MANSONIA TITILLANS 519 



dorsal hair, the band expanding ventrally to half the width of the segment. 

 Lateral comb of eighth segment of five slender widely separated teeth. Eighth 

 segment elevated dorsally to the air-tube, which is short, conical, the apical por- 

 tion attenuated, bearing a tuft of four hairs on each side near the middle and a 

 pair of filaments at base of apical projection ; this consists of two thick lamellae 

 with a group of hooks at the tip and two or three stout teeth on the anterior 

 aspect mesially. Anal segment long and slender, four times as long as wide, 

 ringed by a chitinous band ; ventral brush small, nearly terminal and preceded 

 by a row of small tufts to middle of segment ; dorsal tuft of a long hair and large 

 tuft on each side. Anal processes four, equal, slender, small, somewhat longer 

 than the width of the last segment. 



Pupa. — Thoracic mass subpyriform, smooth ; no dorsal tuft. Abdominal seg- 

 ments strongly prominent on the posterior margin, with a pair of thick spine- 

 like hairs. Anal paddles elliptical, narrow, with notched tip. Eespiratory tubes 

 slender, slightly expanding, the orifice large with a flap on the outer side half as 

 long as the tube, with lateral membrane on each side not quite reaching tip. 



Mr. H. W. B. Moore has published the following observations on the life 

 history, made in British Guiana : 



" Mansonia titillans is one of the commonest mosquitoes of tropical South 

 America, abounding especially in coast regions and along the banks of rivers. 

 It is present with us throughout the year in greater or less numbers. Even in 

 the height of the dry season it is here to annoy us. The larva has remained un- 

 known. I had been hunting for it, and had searched to no purpose swamps, 

 trenches and water-holes at morning, noon and evening. I also had tried over a 

 dozen times to get the larvae from eggs by allowing the mosquitoes to suck my 

 blood and then enclosing them in jars. In no instance did even one so much as 

 deposit eggs. Now it happened that I was dipping with a calabash in one of the 

 Kitty sweet-water canals for larvae of two other mosquitoes, which can always be 

 found there. The water was pretty thickly coated with the aquatic plants 

 Salvinia and Pistia. One of my dippings brought up a portion of Pistia, which 

 I threw back. After pouring out most of the water I noticed a large, stout 

 whitish brown larva wriggling at the bottom of the calabash among the thick 

 rust-brown stuff dislodged from the roots of the plant. At first sight I thought 

 it was a dragon-fly larva, but, its actions making me suspicious, I turned it into 

 my collecting tin for further examination. On arriving at the Museum a cursory 

 examination showed it was a mosquito larva new to me, and the biggest I had 

 as yet come across. Next afternoon I returned to the same trench and soon dis- 

 covered that by taking up Pistia and shaking the roots vigorously in water in my 

 calabash that I could get in a short time quite a number of these big brown larvae. 

 Last week the adult mosquito began coming out, and it is Mansonia titillans." 



The siphon of the larva " is characteristic, being short, conical, tapering to a 

 point, black at the apex, and almost in a straight line with the length of the body. 

 Its resting position is also characteristic, it hangs vertical, it likes to suspend 

 itseH among the roots of the green rosette-like plant Pistia and its general rusty 

 brown colour harmonizes well with the colour of the muck about the roots. In 

 lifting the plant from the water the larvae come up with it entangled in its roots. 

 The pupa has peculiar long siphons, that curve forwards and then outwards, and 

 end in a point." 



Dyar and Knab commented on Mr. Moore's discovery as follows : 



" Mr. Moore has been kind enough to send us preserved larvas and pupae. It 

 is clear from their structure that both the larva and pupa are attached to the 

 roots of the Pistia from which they get their air. The apical portion of the 

 breathing tube of the larva of Mansonia titillans is shorter and stouter than in 



