256 PROCEEDINGS OF THE NATIONAL MUSEUM vol. us 



Mezira guianensis, new species 



Female. — Resembles M. carioca in general aspect, but larger, with 

 finer setigerous granulation, of same general ferrugineous color; an- 

 tennae slender, relatively longer, 1.7 times as long as head (1.4 times 

 in M. carioca) ; anterior process of head relatively wider anteriorly; 

 anterolateral angles of pronotum more rounded, equally expanded 

 forward and sideways; apical border of corium more rounded; posterior 

 half of abdomen more evenly rounded. 



The main difference between these two species lies in the last abdom- 

 inal segments. In M. carioca these segments are short, lobes of VIII 

 (paratergites) larger, produced posteriorly, parallel to each other, 

 regularly rounded apicaUy, reaching to middle of short, deeply exca- 

 vated apically segment IX. In M. guianensis segment VIII a little 

 longer, lobes of VIII smaller, convergent, reaching only to basal third 

 of IX. The latter segment has convergent lateral margins and is 

 barely excavated at apex. 



Measurements. — Head shorter than width through eyes (33:38), 

 or across dentiform postocular tubercles (33:42); proportions of an- 

 tennal segments 15:11:19:11; pronotum (40 : (65) : 81) ; scuteUum 

 (40:48); abdomen maximal width across segment IV (120:96). 



Length 7.8 mm. Width of pronotum 2.70 mm. Width of abdomen 

 3.20 mm. 



HoLOTYPE. — Female, Tumatumari, Potaro River, British Guiana, 

 June 29, 1927, Drake Collection (USNM type 65800). 



Mezira barberi, new species 



Male. — AUied to M. regularis (Champion) , but somewhat smaller, 

 anterior process of head relatively shorter, and not dilated anteriorly; 

 antenniferous tubercles also shorter, only slightly longer than longi- 

 tudinal diameter of eye (7:5), whereas in M. regularis they are dis- 

 tinctly longer (9:5.5). Third antennal segment only one and a half 

 times longer than second (twice as long in M. regularis). 



Head shorter than width across eyes (22.5:24), anterior process 

 robust, constricted in middle, rounded apically, tip slightly incised, 

 almost reaching to apex of first antennal segment. Antenniferous 

 tubercles acute, slightly divergent, reaching almost to middle of 

 first antennal segment. Eyes exserted. Postocular tubercles spini- 

 form, slightly exceeding outer border of eyes; infraocular carinas 

 moderately high, crenulate. Vertex with V-form group of setig- 

 erous granulae. Antennae moderately slender, less than twice as 

 long as head (38:22.5); proportions of antennal segments 10.5:8:12:7.5. 

 Rostrum reaching almost to base of rostral groove. 



Pronotum less than half as long as wide across humeri (25:57); 

 collum tiny, slightly incised at middle; anterolateral angles explanate, 



