MEGAEHINUS POETOEICENSIS 961 



brilliant light blue scales over roots of wings. Seutellum light greenish-blue 

 scaled at the middle, silvery-blue at the sides. Abdomen elongate ; dorsal vesti- 

 ture deep metallic-blue, seventh and eighth segments brilliant violet; sides of 

 segments silver marked ; claspers violet scaled ; venter silver scaled, with a rather 

 broad metallic-blue median stripe, eighth segment violet at base, sUvery at tip ; 

 lateral ciliation short, delicate, and pale. Wiags narrow; basal cross-vein 

 oblique, in one specimen reaching the fourth vein far behiud a very small 

 anterior cross-vein; in the two other specimens the cross-veins are contiguous 

 or nearly so. Legs slender; vestiture very dark blue and purple, knees white; 

 under sides of femora golden scaled; front tibiae with brassy scales on inner 

 side, middle tibiae with brassy scales on outer side ; fourth segment of hind tarsi 

 brilliant white, black at apex. Claw formula, 1.0-1.0-0.0. 



Length : Body 7 to 9 mm. ; wing 6 to 9 mm. 



Genitalia (plate 36, fig. 240) : Side-pieces over twice as long as wide, sharply 

 tapered to a narrow rounded tip ; basal lobe, low, rounded, with coarse setae on 

 summit and small ones basally. Clasp-filament long and slender, nearly as long 

 as side-piece, smooth, with a long articulated terminal spine. Harpes large, 

 prominent, concave, with revolute margins, tip bent outward, acuminate, with 

 several minute setae. Unci with elliptical base, tips slender and produced, serrate 

 within. Basal appendages remote, rounded, setose, connected by a broad, shallow 

 emargination. 



Larva, Stage IV (plate 137', fig. 440) . — Head subquadrate, longer than wide, 

 sides nearly straight, antennae on a slight prominence ; front deeply emarginate 

 at middle, a prominent lobe on each side of it. Antennae rather long, slender, 

 cylindrical, scarcely tapered terminally, smooth; two separate hairs at outer 

 fourth followed by a short multiple tuft; three small terminal digits and a seta. 

 Mouth-brushes inserted on anterior lobes of head, lamellate, folded downward 

 and backward. Mental plate broadly triangular, an apical tooth in a shallow 

 sinus; nine stout subequal teeth on each side; other toothed plates superposed. 

 Mandible quadrangular, straight without, smooth ; two branched appendages at 

 the angle before tip; an outer row of coarse cilia; terminal dentition of five 

 very large teeth, ensiform, the third and fifth smaller. Maxilla rounded quad- 

 rangular, excavate at tip, basal angle ivith a group of flattened appendages with 

 recurved tips ; inner angle with shorter filaments ; palpus nearly separated by a 

 suture, erect, columnar, flat at tip, smooth, with rudimentary terminal digits. 

 Thorax rounded, about as long as wide; lateral hairs short, very stout, the 

 heaviest ones spinulose. Abdomen stout, the segments angled on the sides, 

 anterior ones narrow and transverse ; hairs abundant, moderately long, all the 

 lateral hairs multiple to fifth segment, double on sixth. Tracheal tubes large, 

 expanded into bladders in the thorax. Air-tube stout, slightly conically tapered 

 outwardly, about two and a half times as long as wide; no pecten; a single tuft 

 near base. A large plate on sides of eighth segment, with two stout spinulose 

 hairs on its posterior margin. Anal segment about as long as wide, ringed by 

 the plate, which is fringed with spines behind; dorsal tufts of two long brushes 

 on each side ; a single spinulose lateral hair ; ventral brush well developed, of 

 branched feathered tufts; anal gills very short, bud-shaped. 



The larvse inhabit water in holes in trees. Mr. Busck found them twice in 

 holes in palm-trunks and once in another tree not specifically mentioned. They 

 feed upon the larvae of Aides mediovittata and other species inhabiting hollow 

 trees. 



Greater Antilles. 



San Francisco Moxmtains, Santo Domingo, September, 1905 (A. Busck) ; 

 Cuba (Osten Sacken, specimen in the Museum of Comparative Zoology, Cam- 

 bridge, Massachusetts). Eeported also from Porto Eico (von Eoder). 



