NO. I BLACK FLIES OF GUATEMALA — DALMAT 225 



toothlike processes, some of them very small. Occipital cleft dome- 

 shaped, its sides almost parallel, its apex slightly pointed (pi. 43, 

 fig. 419). 



Thorax and Abdomen: Pseudopod (thoracic proleg) with 15-21 

 rows of hooks on its apex ; postclypeal sclerites minute, hardly visible. 

 Posterior sucker with 64-72 rows of hooks. Anal gills with 3 main 

 divisions, each with from 3-5 fingerlike projections. Anterior arms of 

 X-shaped sclerite each with a wedge-shaped, well-pigmented patch 

 along its outer margin which appears to reach the base of the posterior 

 arms ; patches completely cover anterior arms ; just in front of the 

 anterior arms and between them and the anal aperture is a raised, 

 reticulated patch with purplish pigmentation; on either side of this, 

 and lateral to the anterior arms, is a bulblike protuberance the apex of 

 which is directed toward the midline ; these are clothed by simple 

 spines ; 4 to 5 rows of rectal scales. Eighth segment with two well- 

 formed, conical ventral papillae; between them and the posterior 

 sucker is a transverse row composed of about 20 heavily sclerotized 

 plaques, the more lateral ones larger and somewhat raised. 



Types. — (^ ; according to the original description, it is in the Museo 

 Zoologico di Parigi ; type locality given as "Mexico (Salle)." 



SIMULIUM (SIMULIUM) OCHRACEUM Walker 



Simulimn ochraceum Walker, Trans. Ent. Soc. London, n. s., vol. 5, p. 332, 1861 

 (original description, female). — FAiRCHru), Ann. Ent. Soc. Amer., vol. 33, 

 No. 4, pp. 706 and 708, figs. 6, 11, 23, and 35, 1940 (?, c?, and pupa).— 

 Vargas, Rev. Inst. Salubr. Enferm. Trop., vol. 3, No. 3, pp. 238-239, figs. 5 

 and 12, 1942 (c? and ? genitalia). 



Eiisimultum ochraceum (Walker), Hoffmann, An. Inst. Biol. Univ. Mexico, 

 vol. 2, pp. 207-218, figs. 3, 4, 8, 12, 14, and 15, 1931(b) (pupa and larva). 



Male (pi. 26, figs. 85-87). — 2.3 mm. long. 



Head: Holoptic. Eyes brown. Antenna 430 /x, long, 11 -segmented, 

 slightly tapering; segment 3>i-|-2, 3>4 + 5, 3>ii; scape, pedicel, 

 and half of first flagellar segment brown, the remainder of the flagel- 

 lum black. Palpi black. Clypeus black, white-pruinose, irregularly 

 covered by long black hairs. 



Thorax : Mesonotum yellow to orange ; a rather narrow band of 

 pale-yellow pruinosity around the periphery except in middle of 

 anterior margin where it is interrupted; few short black hairs con- 

 centrated principally on the anterior and posterior fourths of the 

 mesonotum. Humeral angles pale yellow, with sparse black hairs. Scu- 

 tellum yellow with pale pruinosity and with long black hairs. Postno- 

 tuni velvety brown, white-pruinose, devoid of hairs. Pleura brown, 



