178 CATALOGUE OF DIPTERA 



f-j- Dish of the sciitel pubescent or bristly. 

 To C. f belong B. sylvaticus—limosus—fenestralis?—clunipes — 



ochripes—zosterce— nivalis ; and many more which it is difficult 



to distinguish. 

 To C. ff B. fuseipennis — vagans, ^c. 



B. nivalis. Niger, hypostomate ferrugineo, alls ahbreviatis. 



(Long. .08.) 

 Dull black : face rusty yellow : legs rufescent : thighs and hind 

 shanks dusky : 2d joint of hind feet twice as long as 1st, scarcely 

 thickened : wings shorter than the abdomen. 

 About the roots of trees during the winter ; leaping far. 



B. Zosterae. Niger, tarsis liiteis, alis denigratis, thorace 

 scutelloque ojjacis planis, antennanim seta alhida. (Long. 

 .06.) 



Thorax with an obsolete depressed line down the back : scutel with 

 only about two pair of bristles at the sides and tip : feet short, 

 yellowish, 2d joint of the hind pair somewhat thickened : wings 

 of an uniform opaque smoky tint: knob of the poisers deep brown. 

 Common upon Zostera, drying on the shore. 



B. fuseipennis. Niger, pedibus piceis, thorace scutelloque 

 ferruginosis setosis, alis fuscis, halteribus luteis. (Long. 

 .09.) 



Resembles B. limosus, but is smaller, and the wings darker : the 

 disk of the scutel, as well as the thorax, set with bristles ; both have 

 a very dull ferruginous tinge: 1st joint of hind feet very broad, 

 2d twice as long, scarcely at all thickened : seta of antennae black. 



Common on marine rejectamenta. 

 B. vagans. Niger, opacus, scutello pubescenie, alis denigratis, 



halteribus luteis. (Long. .06.) 

 Resembles B. Zosterce, but the disk of the scutel is pubescent and 



not so flat : feet short, fore pair a little dilated. 

 ( Division F.) Transverse nervures approximate, 4th and r)th 



longitudinal not approaching each other, 3d curved to the rib 



beyond the middle. 



Borborus aterrimus. Ater, holosericeus, alis albis, seta anten- 



narum albida. (Long. .04.) 

 Feet short, fore pair a little dilated : seta pubescent whitish : wings 



opaque, milk-white : rib blackish, the other nervures inconspicuous. 



