234 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



segmented, surpassing the basal stalk of the cephalic fan ; segment i 

 dark brown, the others lighter; segment 2 about one and one-third 

 times the length of segment i which is about one and one-third times 

 the length of segment 3 ; segments i and 2 with transverse striations. 

 Submentum with 9 apical teeth, triangular in shape, the central one 

 and the two outermost teeth larger than the others ; ventrolateral row 

 composed of 7 very thick hairs that appear to be 3- or 4-branched 

 near the apex ; lateral margin of submentum with 6 toothlike serra- 

 tions, the most apical one more heavily pigmented than the others and 

 appearing to emerge from the lateral margin of the outermost of the 

 apical teeth. Occipital cleft deep, like half of a hexagon in shape, the 

 apex pointed (pi. 43, fig. 421). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 34 

 rows of hooks on its apex ; postclypeal sclerites minute and poorly 

 sclerotized. Posterior sucker with 81-88 rows of hooks. Anal gills 

 with 3 main divisions, each with from 4-6 fingerlike projections; 

 usually the middle division has 6 and the two outer divisions 4 each. 

 Anterior and posterior arms of X-shaped sclerite well sclerotized ; 

 broad, almost rectangular, pigmented patch on each of the anterior 

 arms, the two patches meeting on the midline between the arms ; outer 

 margin of patches almost reaching posterior arms ; no rectal scales. 

 Eighth segment with very small, transparent, hardly visible, ventral 

 papillae ; no sclerotized plaques. 



Types. — Holotype ($) mounted, in part, on slides, the rest on a 

 pin; allotype ((^) mounted on slides; paratypes (2 $5) on pins. 

 These types, as well as 20 pupae preserved in alcohol, are in the col- 

 lection of the Instituto de Salubridad y Enfermedades Tropicales, 

 Mexico City; collected from Cascada de Teocelo, Veracruz, Mexico, 

 May 1946. 



SIMULIUM (SIMULIUM) TRICORNIS De Leon 



Simulium tricornis DeLeon, Bol. Sanit. Guatemala, vol. 52, p. 68, fig. 4, 1944 



(original description, pupal respiratory apparatus). 

 Simulium {Simulium) tricornis De Leon, Vargas, Martinez, and Diaz, Rev. 



Inst. Salubr. Enferm. Trop., vol. 7, No. 3, pp. 155-157 and 176, figs. 110-116, 



122, and 151, 1946 {<S, $, pupa, and larva). 



Male (pi. 26, figs. 91-93). — 3.4 mm. long. 



Head: Holoptic. Eyes reddish brown with yellowish cast. An- 

 tenna 630 /A long, 1 1 -segmented, slightly tapering; segment 3<i-f2, 

 3 = 4+5, 3=11 ; black except for the apex of the pedicel and base of 

 first flagellar segment which are brown. Palpi black. Clypeus black, 

 white-pruinose, with 2 rows of long black hairs along the margins. 



