148 CALIFORNIA ACADF-MY OF SCIENCES. [Proc. 3D See. 



Ar>arosylus direptor, sp. nov. 

 Plate IV, Figs. 7-10. 



. 'Male. — Length of body 2.5 mm.; length of wing 3.5 mm. Face dull me- 

 tallic green, rather thickly covered with pale dust, palpi somewhat smaller 

 than in the preceding species, black, with black hairs. Antennas black, first 

 and second joints as in the preceding species, third joint shorter and more 

 oblong, owing to a blunt projection on the ventral side near the insertion of 

 the arista; basal segment of the arista short, hairy; apical segment long and 

 bare. There are a few prominent bristles on the third joint similar to those 

 found in A. prcedator. Cilia of the superior and inferior orbits black, not 

 very prominent. Thoracic dorsum metallic green, opaque, with a thick layer 

 of brownish dust; acrostichal and dorsal bristles prominent, black. Pleurae 

 and scutellum as in A. prcedator. Abdomen metallic green, overlaid with 

 white dust and covered with short black hairs; the six segments are of nearly 

 uniform length and taper gradually to the insertion of the hypopygium. 

 Hypopygium smaller than in the preceding species. Its swollen and hairless 

 base bears the scale-like rudiment of the seventh segment on the left side. 

 The pair of outer appendages is considerably shorter than in A. prcedator 

 and directed forwards from their insertions. They are black and covered 

 with black bristles, those on the mesial surfaces being short and stubby. 

 The yellowish inner appendages are concealed, with the exception of the 

 penis, which is long and delicate, and passes backwards between the outer 

 appendages, so that its recurved end projects a short distance beyond the tip 

 of the abdomen. Legs dull metallic green, blacker distally, covered with 

 pale dust and black bristly hairs. Fore coxae with conspicuous black hairs 

 on their front faces, fore femora thickened proximally, without spines on 

 their lower faces, but with a row of long black cilia along their upper surfaces. 

 The strigil-like comb of pale hairs near the tip of the fore tibia is more prom- 

 inent than in A. prcedator. Hind femur with a row of black cilia on the 

 upper surface of its proximal half. Wings without prominent anal angle, 

 gray, somewhat opaque; venation as in the preceding species. A large black 

 blotch covers the distal end of the discal cell and the posterior cross-vein, and 

 extends up half-way between the third and fourth veins. Halteres dull light 

 yellow. Cilia of the tegulae black. 



Female. — Length of body 3-3.5 mm.; length of wing 3.5-4 mm. Apart 

 from the primary sexual characters the female differs from the male only in 

 having a somewhat broader face. The female even has the cilia on the fore 

 and hind femora, a character which we should hardly expect to find in this 

 sex. 



The above description is drawn from one male and six 

 female specimens. These were taken in company with A. 

 ■prcedator at Pacific Grove, California, July 5th and 31st. 

 Though rarer than the last mentioned species, A. direptor 

 was frequently observed flying about among the sea weeds. 

 In the living insect the black spots of the two wings coincide 



