346 Annals Entomological Society of America Vol, 
Pachyrhina trinidadensis, sp. n. 
Similar to macrosterna but antenne darker; three distinct brown 
thoracic stripes; dorsal apical appendage of the o genitalia chisel- 
shaped, sub-truncated at its apex. 
& Length, 11 mm.; wing, 10.8 mm.; antennz, about 4.5 mm. 
Q 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. 
Middle leg, femur, 8.5 mm.; tibia, 8.8 mm. 
Hind leg, femur, 9 mm.; tibia, 9.9 mm. 
& Head: Anterior prolongation of the front and the palp1 brown. 
Antenne, two basal segments light orange-yellow; 3d segment, basal 
half brown, apical half yellow, remaining segments brown, extreme apice 
of each segment yellowish, this yellow color becoming obsolete on the 
outer segments. Front, vertex and occiput brown, the center of the 
vertex broadly shiny and brighter brown. 
Thorax: Pronotum very pale yellowish-white, not shining; 
mesonotum shiny, prescutum light yellow with three dark brown uni- 
form stripes; the middle stripe is broadest on the anterior portion of the 
sclerite, rather narrower behind; the lateral stripes bent strongly 
ventrad 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; pleuree pale with a sparse greyish pollen. Halteres pale, 
gradually darkening to the brown knob. Legs: coxee and trochanters 
light clear yellow; femora brown, 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: Tergum brownish, the lateral margins of the sclerites 
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. Hypopygium (see Fig. j); 7th and 8th tergites and 7th 
sternite as in macrosterna; Sth sternite with the caudal denticula (d) 
about equal to the cephalic one; 9th sternite (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. j2); 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. j,) 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 sternite which it almost touches; at its base, a 
smail hair-bearing projection; the margin of the appendage below the 
large spine curves 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. 
