ZooL.— Vol. II.] WHEELER— DOLICHOPODID/E. 67 



Cheeks very narrow. Postocular cilia above short and black, below long 

 and abundant, silvery white. Thorax and scutellum metallic crimson, the 

 former bordered with metallic green and bearing a pair of dark purple vittae, 

 one on either side of the single row of very short acrostichal bristles. Lat- 

 eral and humeral bristles very few, scattered. Abdomen somewhat longer 

 than the thorax, gradually tapering, somewhat compressed dorsoventrally, 

 metallic green, with cupreous reflections, covered with pale dust, so that it is 

 distinctly less shining than the thorax. Hypopygium black, concealed; 

 stemite of fourth abdominal segment with a deep notch in its posterior 

 border. Pleurae, coxae and legs metallic green dusted with white; anterior 

 surfaces of fore coxae with conspicuously long, silky white hairs. Fore femora 

 thickened towards the base, gracefully attenuated towards the tip, bearing a 

 series of about six blunt black spines on the lower anterior surface near the 

 base. Fore tibiae with a pair of spines at the tip and a series of minute, 

 thick-set tooth-like spines along the lower (inner) surface. Fifth joint of mid- 

 dle tarsi dilated and flattened, as broad as long. Claws and pulvilli not so 

 much enlarged as in many other species of Hydrophorus. Wings grayish 

 hyaline, broader at the base than at the apex, owing to a distinct bulging of 

 the costa as far as the tip of the first vein, which enters the costa at the mid- 

 dle of the wing. Tip of third vein gradually bent down towards the fourth. 

 Veins dark brown at their tips, bright honey yellow at the base, the costa 

 being honey yellow to a point midway between the tips of the first and sec- 

 ond veins. Halteres and tegute yellow, the latter with white cilia. 



Female. Length 4 mm.; length of wing 4 mm. Like the male except in 

 the following respects: Face covered with light yellow dust. Front covered 

 with yellow dust except when seen from above; then it appears cupreous, 

 passing into metallic green on the occiput. Abdomen more flattened, fourth 

 sternite without a notch. White hairs on fore coxae much shorter. Fore 

 femora with a row of short, pointed spines extending along its whole lower 

 surface. Tooth-like spines on the lower surface of the fore tibia much longer 

 and further apart than in the male. Fifth joint of middle tarsi not dilated. 



A male and female collected by Professor J. M. Aldrich 

 at Battle Creek, Michigan, during July, 1897. 



The sexual differences in the armature of the fore legs 

 are peculiar. It can hardly be doubted that the female rep- 

 resents the more primitive condition, although she seems to 

 have the more pronounced development of spines. 



68. Hydrophorus Magdalenae, sp. nov, 



Plate IV, Fig. 124. 



Male. Length 4 mm.; length of wing 5.5 mm. Proboscis dull black, palpi 

 brown. Face metallic green, lower two-thirds thickly covered with snow- 

 white dust; upper third with a little ochre-yellow dust in a median depression 

 and along the orbits. Antennae black, of the usual size and shape; arista 

 rather long. Front and occiput metallic golden green, the former thickly, the 



