PSOROPHORA CINGTJLATUS 599 



cleft at tip, forming two teeth directed outwardly. Harpagones with a slender 

 ligulate base and broadly triangular tip bearing six stout setae on elevated bases. 

 Unci contiguous, forming a stout cone. 



Larva, Stage IV. — Head rounded, wider than long, narrowed before the eyes, 

 a slight notch at insertion of antennae, front margin broadly arcuate. Antennae 

 very long and prominent, spined all over ; a large tuft before middle arising from 

 a slight notch ; two spines before tip, another spine, a short spine and a digit at 

 apex. Eyes large, transverse, pointed. Mental plate elongate triangular, with a 

 central tooth and fourteen on each side, becoming more remote and pointed 

 basally, the last one minute and remote. Mandible quadrangular ; a filament and 

 small tuft of hairs before tip ; an outer row of cilia from a collar ; a row of small 

 simple hairs from angular projecting bases along outer margin ; dentition of four 

 teeth on a small process, first and fourth longest; a large tooth at base, with a 

 row of small serrations, a long serrate filament, and two short feathered hairs 

 within ; process below elongate, furcate ; a row of hairs along its outer margin ; 

 basal angle slight, with a row of five hairs within ; a row of long hairs at base. 

 Maxilla rounded elliptical, divided by a broad crooked suture, inner half covered 

 with coarse spines ; a tuft of coarse hairs at tip ; outer half with a single articu- 

 lated filament at bend of suture, a spine on other side. Palpus stout, short, with 

 four irregular terminal digits. Thorax rounded, wider than long, robust ; hairs 

 abundant but not long. Abdomen stout, anterior segments shorter ; lateral hairs 

 of first two segments multiple, double on third to fifth, single on sixth. 

 Tracheal tubes broad, band-shaped. Air-tube large, strongly inflated, tapered 

 at outer half, three times as long as wide; pecten of four teeth scattered over 

 basal third of tube ; single spine long, with one or two basal branches. Lateral 

 comb of eighth segment of six separate scales ; single scale elliptical, with a long 

 stout terminal spine and a subterminal one on each side, less than half as long 

 as terminal one. Anal segment wider than long, ringed by the plate ; dorsal tuft 

 a long hair and brush on each side ; a small lateral tuft ; ventral brush well de- 

 veloped, extending along ventral line to base. Anal gills long, twice as long as 

 the segment, tapered to a sharp tip ; each with a slight central trachea. 



The larvae occur in ground-pools. Mr. Busck got them in an open pool near 

 a village and in low, open pools in a sugar-cane field. 



North Coast of South America, Island of Trinidad. 



Cedros, Trinidad, June 14, 1905 (A. Busck) ; San Juan, Trinidad, June 7, 

 1905 (A. Busck) ; Trinidad (F. W. Urich). Reported from South America 

 (Pabricius) and British Guiana (Theobald) . 



Psorophora cingulatus is extremely close to Psorophora apicalis (Theobald) 

 (Cidex apicalis Theobald, Mon. Culic, iii, 171, 1903), of which we possess a 

 specimen from Brazil, by the kindness of Dr. Arthur Neiva. There is a slight 

 difference in the shape of the wing-scales, those of the present species being blunt 

 at the tip, while those of apicalis are pointed. We feel obliged to keep the species 

 separate, although we doubt very much whether they are not really only geo- 

 graphical forms. We can not observe any other differences between the forms. 

 Theobald's identification of the species treated here with Arribdlzaga's Tcenior- 

 hynchus confinnis we do not accept on account of the geographical discontinuity. 

 If either species is the same as the Argentine one, it should be apicalis and not 

 cingulatus. We think, however, that neither is so and that the Argentine form, 

 when rediscovered, will prove abundantly distinct from both. Dr. Neiva has 

 examined Fabricius' type of cingulatus and writes us that he is convinced that 

 it is the same as apicalis Theobald. Owing to the geographical distribution of 

 these forms, and to the fact that the type of cingulatus probably came from the 

 Guianas, we feel obliged to consider cingulatus as referring to the northern 

 form which we called indoctum rather than to the southern apicalis. The figure 



