346 Amials Entomological Society of America [Vol. V, 



Pachyrhina trinidadensis, sp. n. 

 Similar to macrosterna but antennae darker; three distinct brown 

 thoracic stripes; dorsal apical appendage of the cf genitalia chisel- 

 shaped, sub-truncated at its apex. 



cf Length, 11 mm.; wing, 10.8 mm.; antennas, about 4. .5 mm. 



9 Length, 12—13.2 mm.; wing, 12.2—12.8 mm. 



Fore leg, femur, 7.7 — 7.8 mm.; tibia, 9.4 — 9.8 mm. 



Aliddle leg, femur, S.5 mm.; tibia, 8.8 mm. 



Hind leg, femur, 9 mm. ; tibia, 9.9 mm. 

 cf Head: Anterior prolongation of the front and the palpi browm. 

 Antennas, two basal seginents light orange-yellow; 3d segment, basal 

 half brown, apical half yellow, remaining segments brown, extreme apice 

 of each segment yellowish, this yellow color becoining obsolete on the 

 outer segments. Front, vertex and occiput browm, the center of the 

 vertex broadly shiny and brighter brown. 



Thorax: Pronottim very pale yellowish-white, not shining; 

 mesonotum shiny, praescutum light yellow \\'ith three dark brown vmi- 

 form stripes; the middle stripe is broadest on the anterior portion of the 

 sclerite, rather narrower behind; the lateral stripes bent strongly 

 ■\'entrad at the pseudosuture {humeral pit or dorso-pleural suture of 

 Osten Sacken); scutum yellowish with two dark brown spots on each 

 lobe; scutellum lighter brown; post notum brownish-yellow, thinly 

 pale pollinose; pleura; pale with a sparse greyish pollen. Halteres pale, 

 gradually darkening to the brown knob. Legs: coxa; and trochanters 

 light clear yellow; femora browoi, the tip narrowly dark brown; tibia 

 and tarsi brownish. Wings: color and venation almost exactly as in 

 macrosterna of Central America (see Fig. h.). 



Abdomen: Tergtun brownish, the lateral margins of the sclcrites 

 clearer yellow, not darker on segments 2 to 4; segment 7 with the 

 basal half dark brown; remainder of tergum and the sternum, brown- 

 ish-yellow. Hypopygimn (see Fig. j); 7th and 8th tergites and 7th 

 stemite as in macrosterna; Sth stemite with the caudal denticula (d) 

 about equal to the cephaHc one; 9th stemite (9s) viewed from the side 

 with an obtuse notch on the ventral face. Apical appendages: The 

 dorsal-lying appendage (c) projects straight backward, enlarged at the 

 apex, chisel-shaped, the outer angles equal, the caudal margin gently 

 concave (see Fig. j.>) ; the appendages lie in a vertical plane and side by 

 side, separated from one another by a distance about equal to the 

 width of one. The second, or ventral, appendage (see Fig. ji) the ventral 

 branch of macrosterna is, apparently, lacking; the dorso-proximal 

 branch is chitinized and bears a sharp spine on the caudal margin, this 

 spine being bent outward (a) ; on the sides of the appendage is a large 

 prominent spine which projects ventrad and outward (x) toward the 

 appendage of the 9th stemite which it almost touches; at its base, a 

 small hair-bearing projection; the margin of the appendage below the 

 large spine air\'es distad, is chitinized on the extreme edge and bears 

 long hairs; I cannot perceive any structure corresponding to the dorso- 

 distal branch of macrosterna; a large pale organ lying between these 

 ventral appendages and just beneath the paired dorsal appendages. 



