170 NEW YORK SJATE MUSEUM 



the next snuall, the following ones again, slender and elongate, 

 the last one small; these are all only thinly haired (flg.3). The 

 eyes round, bare, the ocelli wanting" (or rudimentary?) ; front 

 broad. The arching of the thorax gradually becomes greater 

 from the head baekward, the transverse suture wanting; scutel- 

 lum short but wide; metathorax moderately large. Abdomen 

 8-jointed, hypopygium somewhat projecting. Legs long; coxae 

 not elongated, the fore femora shortest, the posterior pair long- 

 est; tibiae without spurs; tarsi of the posterior pair of legs ex- 

 tremely slender, and at least as long as the femora and tibiae 

 taken together, the metatarsus about twice as long as the follow- 

 ing joints taken together, apical joints small, the sole of the clawed 

 joint bristly, the claws quite long and bent; the halteres promi- 

 nent. Wings long and narrow ; venation as shown in figs. 1 and 2. 

 The first figure is from Y. d. Wulp (1S77) the second after Meigen 

 (1818). No North American species have been described. 



Genus 31. Hydrobaenus Fries 



Vetensk. Akad. Handl., 1829. 176. 1830 

 Psilocerus Rutlie, Isis. XI. 1207. 1831 

 (P1.34, figs. 2 to 11) 

 Fries (1830) describes the larva and pupa at considerable length 

 and gives figures illustrating details of each ; the latter are repro- 

 duced on pl.34, figs. 2 to 5 and 8. 



Larva. The larva is described as being 4 mm. in length, green- 

 ish in color, quite slender, and cylindrical. The head (fig.2) is 

 small, obcordate and black. The antennae are three-jointed. On 

 the ventral side of the first thoracic segment is a pair of feet with 

 setae (fig.3). On the dorsal surface of the eleventh abdominal 

 segment are two cylindrical processes, the extremity of each with 

 a tuft of long hairs. On the venti-al surface of this segment are 

 the blood gills, two in nun'iber and shorter than in C h i r o n o- 

 m u s. The twelfth segment has the usual anal feet and four blood 

 gills, the latter, however, differing fnmi C h i ro n o ni u s in hav- 

 ing at the apex of each a little tuft of hairs. 



Pupa. (Figs. 5 and 8) Thorax with short and narrow respira- 

 tory tubes. The caudal end is ])rovided with two tufts of long 

 hairs. The species shown by Fries is H. Ingubris, an 

 European species. 



Imago. Very small black species, the males as well as the 

 females of whicli have the antennae with short hairs. Head small. 



