G. blanda. 



2 



230 PROCEEDINGS OP THE ACADEMY OF 



(like Meig. i. tab. vii. f. 7 J of moderate length ; naked, with two radial and no 

 petiolate arete. The second radial area is very short, taking its origin about the 

 middle of the cubital; the upper branch of the radial fork runs obliquely towards the 

 anterior margin ; mediastinal vein short, joining the costal nearly opposite the 

 origin of the petiole ; discal areolet extant or wanting ; stigmatical cross-vein 

 wanting. Forceps of the J 1 (fig. 16 and 17, G. blanda and G. cogna- 

 te 1 1 a ,) consists of two moveable basal pieces, with four elongated appendages 

 attached to each of them ; these appendages are clothed with hairs or bristles, 

 and armed with spines. Ovipositor of the 9 moderately long, consisting, as 

 usual of two pairs of valves ; the upper pair long, arcuated. 



The peculiarities of this genus consist, chiefly, in the neuration of the wing, 

 the structure of the tf forceps and the coloring, in which the sulphur-yellow 



prevails. 



It is not easy to find for G o n o m y i a an appropriate location in the system ; 

 it stands as an isolated, sharply defined group, bearing no apparent affinity to 

 any other group of the family. The number of joints of its antenna, the smooth 

 ungues, the disinct pulvilli, and the presence of the second, although almost 

 rudimental, radial area, determined me to locate it, provisionally, in the same 

 group with Erioptera. 



The European Limnobia te n el la Meig. belongs to this genus. It wassent 

 to Meigen by Megerle under the name of Gonomyia tenella (conf. Meigen, 

 vol. I. p. 146). Mr. Stephens, in his Catalogue of British Insects, (1829), and 

 Mr. Curtis, in his "Guide." (1837), have again applied this generic name to 

 this species, but without defining the genus. 



Analytical Table. 



1. Wings spotted, 

 Wings not spotted, 



2. Femora with a distinct brown ring at the tip ; knob of halteres lemon- 



yellow, Bk sulphurella. 



Femora without brown rings at the tip, 3 



3. Antennae orange at the base, G- cognatella. 

 Antennas entirely black, G. subcinerea. 



G. sulphurella. Sulphureo-flava, fusco-maculata ; antennis basi auran- 

 tiacis, in J 1 verticillis longis; femoribus annulo fusco ; areola discoidali (in 

 speciminibus typicis) clausa ; long. lin. 2 2. 



Front and vertex sulphur-yellow, infuscated in the middle ; proboscis, palpi 

 and antennas brown ; basal joints of the latter bright orange ; flagellum of the 

 tf incrassated at the base and slender beyond it, with long, feathery verticils ; 

 that of the 9 filiform with short verticils. Collare sulphur, yellow ; praescu- 

 tum and scutum light brown, yellow on the margins ; scutellum yellow with 

 a brown line in the middle ; metathorax yellowish, infuscated in the middle ; 

 pleura? yellow along the margins of the praescutum ; a yellow stripe, margined 

 with brown, runs from the fore coxae backwards ; halteres yellow ; knob lemon- 

 yellow ; coxa? pale yellow, with a brown ring at the tip ; femora slightly in- 

 crassated at the tip, with a yellow ring beyond the middle and a brown ring 

 near the tip, which is yellow ; anterior pair of femora darker, their tip brown ; 

 tibise tawny, infuscated at tip ; tarsi fuscous. Abdomen of the c? lemon- 

 yellow ; base of the segments brown, genitals yellow; abdomen of the $ 

 brownish ; posterior margins of the segments of the tergum yellow ; genitals 

 ferruginous. Wings slightly gray, pale at the base, stigma pale ; oblique vein 

 very short, almost perpendicular. (Conf. Schummel, 1. c. tab. ii. f. 2.) The 

 discal areolet is closed in the normal specimens ; among 15 $ and 9 speci- 

 mens which I have before me, it is open in a single one only. 

 Washington, Trenton Falls, etc. Spring and Summer (nob.) 



G. cognatella. Sulphureo-flava, fusco maculata, antennis basi auran- 



[Aug. 



