NATURAL SCIENCES OP PHILADELPHIA. 231 



I 



tiacis, in $ dense pubescentibus, verticillis brevibus ; pedibus uni coloribus ; 

 areola discoidali aperta ; long. lin. 2 2. 



Very like the preceding, but easily distinguished by the following charac- 

 ters : 1st. The antennae of the tf are covered on every joint with a short, 

 dense pubescence, which, being interrupted at the articulations, makes the 

 antennae appear moniliform ; 2d. The halteres (both stem and knob) are in- 

 fuscated ; 3d. The plurae are yellow, with a brown stripe ; 4th. The feet are 

 uniformly pale tawny ; only the tips of the tarsi darker ; 5th. The upper 

 branch of the radial fork is more oblique and therefore longer ; 6th. The 

 discal areolet is open (at least in the normal specimens ;) 7th. The forceps of 

 the tf has a different structure. 



Five $ and two $ specimens ; Washington (nob.) 



G. subcinerea. Sulphureo-flava, thoracis disco cinereo-fusco, antennis 

 nigris ; pedibus unicoloribus ; long. lin. 2| 2. 



Very like G. cognatella, but easily recognizable by the following char- 

 acters : the pleurae are yellow ; the brown parts of the thorax have a peculiar 

 greyish tinge ; the antennae are uniformly black ; those of the <^ have moder- 

 ately long verticils, the pubescence is not so distinct ; the discal areolet (in the 

 normal specimens) is closed ; the halteres are very slightly infuscated. 



Twelve $ and 9 specimens ; the discal areolet of one of them is open. 

 Washington, Trenton Falls, etc. (nob.) 



This species seems to resemble Limnobia shistacea Schum. (I.e. p. 

 146), but the upper branch of its radial fork is more oblique and arcuated 

 than that of the latter species, judging from Schummel's figure. 



Gr. b 1 a n d a . Flavo-variegata ; alae stigmate et marginis anterioris parte 

 apicali fuscis ; venulis transversis infuscatis ; long. lin. 2 2. 



Proboscis cinereous, margined with yellow on the upper side ; front and 

 vertex cinereous, margined with yellow along the eyes ; antennae brown ; two 

 basal joints yellow. Praescutum pale cinereous, with two approximated brown- 

 ish stripes in the middle ; lateral stripes hardly distinct ; scutum, scutellum 

 and metathorax yellowish cinereous, marked with brownish spots ; plurae pale 

 yellow, slightly hoary ; halteres dusky, with dark knobs ; feet pale, tips of 

 femora, tibiae and tarsi infuscated. Tergum brownish cinereous ; lateral and 

 posterior margins of the segments yellow ; venter sulphur yellow ; $ forceps 

 yellow with black appendages ; 9 ovipositor ferruginous. Wings with clouded 

 cross-veins and black dots at the anastomoses of the veins ; the stigma and the 

 portion of the anterior margin between the stigma and the tip are blackish ; 

 in some specimens there is a short stump of a vein near the origin of the 

 petiole. 



Four tf and $ specimens; Washington, Trenton Falls (nob.) 



Limnophila nob. 



Two radial areae ; mediastinal cross-vein near the tip of the mediastinal 

 vein, and always posterior to the origin of petiole ; petiolated areolet in most 

 cases extant ; sometimes wanting ; (in the first case the neuration is more or 

 less like Meig. i. tab. iv. f. 20, or tab. vi. f. 2 ; in the second like Meig. v. 

 f. 4.) ; antennae 16-jointed ;* palpi mnch shorter than the head ; joints nearly 

 of the same length; (except inL. macrocera Say, the palpi of which are 

 nearly as long as the head, the last joint being elongated) ; proboscis short ; 

 labrum transverse; tibiae armed with spurs at the tip; pulvilli distinct; 

 ungues smooth ; forceps of the tf consisting of two cylindrical or subcylindri- 

 cal basal pieces, with two coriaceous or horny, generally falciform appendages 

 attached to them. (Fig. 24, 25, 26, 27, 28.) 



*Except in the 12th section, which has been temporarily located in this genus, and in 

 which the antennae are apparently 17-jointed. 



1859.] 



