250 PROCEEDINGS OP THE ACADEMY OP , 



pale, very slightly dusky on the knob ; coxae cinereous, trochanters and base 

 of femora pale ; feet black. Abdomen blackish cinereous, indistinctly whitish 

 along the lateral margins ; male genitals cinereous ; female ovipositor ferrugi- 

 nous. Wings tinged with cinereous ; stigma pale, indistinct, situated be- 

 tween the stigmatical and supplementary cross-vein ; neuration like tab. xxx. 

 f. 7, of Walker's Ins. Brit. Dipt. vol. iii., only the petiole of the lower fork is 

 shorter than the fork itself, and the pubescence of the veins is not so apparent 

 as in the figure. 



Seven tf and two 9 specimens, taken near Washington, early in April. 

 They were flying along the surface of a little stream in the woods and copu- 

 lating. 



One of the ^ specimens has a discal areolet on both wings ; it is formed by 

 a cross-vein which connects the lowest fork, near its origin, with the next ex- 

 terno-medial vein. 



Some of the specimens have a stump of a vein near the origin of the 

 petiole. 



Observation. Both $ and $ of D. rivularis have been described above 

 as having short antennae. At least I found such specimens in copulation. But 

 besides the males with short antennae, I found, on the same day and in the 

 same locality, two males, having antennae twice as long as head and thorax 

 together, with 13 nearly cylindrical, elongated, densely pubescent joints ; the 

 joints of the flagellum are of nearly equal length, except the last one, which 

 is shorter. The other characters of the body and the wings of these specimens 

 agree- entirely with Dicranota rivularis, except that the vertex, the knob 

 of the halteres and the stigma are more distinctly infuscated. The specimens 

 are probably the normal representatives of the male, the more so as D. G u e r i- 

 n i i Zett., has also long antennae. What the males with short antennae, which 

 I found in copulation, are, further investigation will show. 



Ula Halid. 



Antennae 17-jointed. (*) Wings with two radial areae, finely pilose on their 

 whole surface. Mediastinal cross-vein far removed from the tip of the mediastinal 

 vein and anterior to the origin of the petiole. Spurs at the tip of the tibiae very 

 short, but distinct. Pulvilli distinct. Ungues smooth. Proboscis elongated, 

 although shorter than the head. Palpi elongated, especially the last joints. Eyes 

 pubescent. 



The characters of this genus, as given by Walker (Ins. Brit. Dipt. iii. 307), 

 agree too well with the specimen in my collection, to admit of any doubt as 

 to the generic identity. The pubescence of the eyes alone is not mentioned, but 

 may have been overlooked. The neuration of the wing of my specimen agrees 

 exactly with Mr. Westwood's figure of the wing of U 1 a in the above quoted 

 work, (1. c. tab. xxvii. fig. 4). With the precision peculiar to him, Mr. West- 

 wood has not even overlooked the position of the mediastinal cross- vein. 

 Schummel's tab. ii. fig. 7, conveys also an idea of the neuration of this 

 genus. 



Ula shows some relation to P e d i c i a in the position of the mediastinal 

 cross-vein, the pubescence of the eyes and the length of the palpi ; but it 

 differs in the length of the antennae, the pilose wings and the position of the 

 last externo-medial vein. The direction of the latter is like that in the majority 

 of the Limnobiae, and not oblique, as in Amalopis and Pedicia. 



The larvae of U 1 a have been found by Dr. Stannius in Agaricus, (Schumm. 

 Limnob. p. 25.) 



The only species I possess seems to be identical with the European Ula 

 pilosa, judging, at least, from its descriptions ; I redescribe it, therefore, 

 under the same name. 



(*)I copy this character from Walker, the tip of the antennte of my single specimen 

 being broken. 



[Aug. 



