190 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



fourth hairs, counting from the base, may be out of ahgnment ; lateral 

 margin of submentum with 5 small toothlike indentations in regular 

 sequence. Occipital cleft somewhat dome-shaped, its apex pointed 

 (pi. 42, fig. 411). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 42-45 

 rows of hooks on its apex ; postclypeal sclerites well sclerotized, small, 

 and well separated. Posterior sucker with 248-255 rows of hooks. 

 Anal gills composed of 3 main branches, bulbous and fleshy, each with 

 from 12-14 fingerlike projections. The X-shaped sclerite simple, well 

 sclerotized ; anterior arms very short ; union of arms of both sides very 

 broad and open ; no pigmented patches, rectal scales or spines ; nu- 

 merous simple spines on each side, between the anterior and posterior 

 arm. No ventral papillae or plaques on eighth segment. 



Types. — !^, in Bellardi collection (present location unknown) ; 

 collected in Tuxpango, Veracruz, Mexico. 



SIMULIUM (DYARELLA) PULVERULENTUM Knab 



Simuliuni pulverulentuni Knab, Insecutor Inscitiae Menstruus, vol. 2, No. 12, 

 pp. 177-178, 1914 (original description, female). — Fairchild, Ann. Ent. Soc. 

 Amer., vol. 33, No. 4, pp. 716-717, figs. 4 and 19, 1940 (c?, 2, and pupa). — 

 Vargas, Diaz, and Martinez, Rev. Inst. Salubr. Enferm, Trop., vol. 4, 

 No. 3, pp. 287-288, figs. 1-2, 1943 (female). — Vargas, Rev. Inst. Salubr. 

 Enferm. Trop., vol. 4, No. 4, figs. 10-18, 1943 (c?, $ leg, and pupa). 



Simuliuni {Dyarella) pulverulentum Knab, Vargas, Martinez, and Diaz, Rev. 

 Inst. Salubr. Enferm. Trop., vol. 7, No. 3, p. 179, fig. 142, 1946 (larva). 



Male (pi. 24, figs. 61-63). — 2.7 mm. long. 



Head : Holoptic. Eyes dark reddish brown. Antenna 460 fi long, 

 1 1 -segmented, slightly tapering; segment 3=i-f-2, 11=9-1-10; seg- 

 ment 3 stalked ; scape, pedicel, and first flagellar segment brown, 

 other segments black. Palpi dark brown. Clypeus white-pruinose. 



Thorax : Mesonotum velvety reddish brown, completely white- 

 pruinose except for one longitudinal shiny brown band along midline, 

 and one on either side of it, all ending at prescutellar region ; long, 

 narrow, golden-yellow, scalelike hairs densely clothe the entire meso- 

 notum, including prescutellar region ; short, brownish hairs along an- 

 terior margin of mesonotum and in prescutellar region ; no long hairs 

 being found in latter region. Humeral angles shiny brown. Pleura 

 evenly white-pruinose. Scutellum shiny brown, with several long tan 

 hairs. Postnotum velvety brown, white-pruinose, without hairs of 

 any kind. Stem of halter brown, the knob pale yellow, cup-shaped. 

 Wings, 2.1 mm. long and 0.9 mm. wide; relation of length of body 

 to wing, 1.3: I ; Sc with basal third pilose; Ri with spines on distal 



