﻿522 BANKS. 



them at this time in order to elicit a further discussion as to their origin 

 and possible significance. I have noted the same organs in the larva? 

 of Worcesteria grata Banks and in those of certain other Culicida?. I 

 hope to present drawings of them in a paper dealing with the life his- 

 tories of the Philippine mosquitoes. 



Abdomen (PL I, fig. 3). — The first segment has a pair of lateral, approximate, 

 pectinate set*, curving forward as on the thorax ; ventrad to this is a tuft of 

 3 simple setae, submediad on the posterior area of the ventrum is a tuft of 3 

 short, simple setae; the second segment is as the first, except that on the 

 sublateral, posterior area is a tuft of 3 to 5 palmate hairs, laterad of which 

 are 3 short, erect setae in a transverse line; the third segment has a single, 

 lateral, pectinate seta, a palmate-hair tuft consisting of 11 to 12 parts, 3 short 

 setae on a line anteriad of the palmate tuft and a small tuft of simple setae 

 posteriad of the pectinate seta, in addition to the ventral tuft; the fourth 

 segment has a small, pectinate seta laterad and a subsidiary tuft of 3 to 4, 

 simple seta? slightly posteriad. The palmate tuft on this segment contains 14 

 hairs and antero-laterad of this is a simple, erect seta, four times the length 

 of the hairs in the tuft; the fifth segment is similar to the fourth, but its 

 palmate tuft contains only 8 hairs ; the sixth segment has several pale, scattering, 

 simple setae on the latero-dorsal area posteriad. Its palmate tuft is composed 

 of 10 to 12 hairs. - The seventh segment is similar to the sixth; the eighth, 

 hearing the respiratory siphonette (PI. I, fig. 6), has a few scattering setae 

 laterad. The ninth has a quadri -pectinate bristle, laterad, near its apex, and 

 a series of 9 very long (twice the length of the segment) pectinate hairs, 

 curving at their tips and articulated on a special, movable tubercle (PI. I, 

 fig. 6), the whole serving the double purpose of rudder and propeller in the 

 locomotion of the insect. At the extreme caudal end of this segment, dorsad 

 to the anal aperture are 4 palmate, brush-like setae, the ventral pair of which 

 has coarser branches than the dorsal, their number being 18 (in 9 pairs) and 

 their extremities being curved. They are used by the insect for anchoring itself 

 to plants on the surface of the water. The whole dorsum of this segment is 

 covered by a single, chitinous sclerite (PI. II, fig. 5) from the middle of each 

 side of which projects a pair of simple, erect setae. 



The tracheal gills (anal gills) (PI. I, fig. 6) are very short as compared 

 with those of Cnlex and fitegomyia larva?, which remain a long time beneath 

 the water. These gills lie immediately around the anus and are about twice 

 as long as broad. 



The length of the larval period is from nine to thirteen days from the hatching 

 of the egg to the transformation to the pupa. During this time the larva 

 molts five times, the first stage being one and one-half to two days, the second two 

 to three, the third two to three, the fourth two to five and the fifth two days. 



The respiratory siphonette (PI. I, figs. 3, 4 and 6). — This organ, situated on 

 the posterior, dorsal area of the eighth segment, which is obliquely truncated 

 to receive it, is of very peculiar structure and merits a detailed description. 

 When open (PI. I, fig. 4) it has the form of an irregular, elongated five-pointed 

 star, the lobes of which are rounded. The anterior lobe is the largest and lies 

 mediad. It is thin, mica-like in appearance, hinged at its base, and has a 

 vitelline, globular tubercle at the median point of the base. This vitelline 

 tubercle fits into a socket when the lobe is closed over the two tracheal apertures, 

 each of which lies a little to one side of the median line. ^Yhen the organ is 

 closed, the two remaining anterior lobes fit against the respective posterior 

 lobes, the latter doubling outward along their axes and inward along their 



