NO. I BLACK FLIES OF GUATEMALA — DALMAT 121 



branches. Mandible with 2 teeth on its inner margin, the basal tooth 

 appearing to arise from the greatly expanded base of the more-distal 

 tooth ; distal tooth much larger than the other, both sharply pointed. 

 Antenna 540-580 /x, long, 4-segmented, surpassing the basal stalk of the 

 cephalic fan ; segment 3 shorter than segment i which is shorter than 

 segment 2; segment 2 about 1.2 times segment i; segments i and 3 

 light brown, segment 3 somewhat lighter than i, segment 2 clear, 

 almost transparent ; segment i with some longitudinal wrinkles but no 

 transverse striations. Submentum with 9 triangular-shaped apical 

 teeth, the central tooth and the outermost tooth at each extremity 

 longer than the others ; all teeth rather sharp-pointed ; ventrolateral row 

 composed of 4 hairs in a straight line, at irregular intervals from one 

 another, all hairs appearing simple ; lateral margin of submentum with 

 strongly marked serrations, about 7 in all, the apical two more heavily 

 sclerotized than the others and appearing to emerge from the lateral 

 margin of the outermost of the apical teeth. Occipital cleft very 

 shallow, angular (pi. 42, fig. 399). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 18-22 

 rows of hooks on its apex ; postclypeal sclerites rather small, like short 

 bars, not very heavily sclerotized, greatly separated. Posterior sucker 

 with 68-75 rows of hooks. Each of the three main divisions of the 

 anal gills simple, like inflated fingers. Posterior arms of X-shaped 

 sclerite well sclerotized, perpendicular to the longitudinal axis of body ; 

 anterior arms well formed, almost at right angles to posterior arms ; a 

 short, well-pigmented, narrow patch along the outer margin of each 

 of the anterior arms, and a small patch between the two anterior arms 

 at their point of convergence ; numerous minute spicules, or granu- 

 losity, between the anterior and posterior arms of each side, also be- 

 tween the two anterior arms at their point of divergence; no rectal 

 scales. Eighth segment with ventral papillae that are very slender 

 and long, giving them a distinctive appearance ; without sclerotized 

 plaques. 



Types. — Originally described from Europe ; location of type un- 

 known. Because of extensive distribution, specimens can be found in 

 collections throughout Europe and the Western Hemisphere. 



SIMULIUM (BYSSODON) BENJAMINI Dalmat 



SiniuHum (Byssodon) benjamini Dalmat, Ann. Ent. Soc. Amer., vol. 45, No. 2, 

 PP- 339-344, figs. 1-7, 1952(b) (original description, ^, ?, and pupa). 



Male (pi. 22, figs. 22-24). — 2.1 mm. long. 



Head : Holoptic. Eyes very dark reddish brown ; length of eyes 

 almost equal to that of thorax. Antenna 330 jx long, ii-segmented, 



