248 PROCEEDINGS OP THE ACADEMY OP 



yellow, femora and tibiae faintly infuscated at the tip ; tarsi tawny, fuscous 

 at tip, spurs short. Tergum yellow ; posterior margins of segments fuscous; 

 first and second segments infuscated, the following with a fuscous stripe along 

 the middle; the two last segments fuscous; genitals of the $ fuscous; of the 

 9 ferruginous. Wings subcinereous ; subcostal and mediastinal areae brown ; 

 this color occupies the whole base of the wing and encroaches also on theprae- 

 brachial and both radial areae ; mediastinal, stigmatical and central cross-veins 

 and origin of petiole clouded with brown. 



This is the normal coloring; but among the eighteen specimens which 

 I have before me only four show it in its full development. All the others 

 are more or less pale about the collare, scutum, scutellum, metathorax 

 and abdomen, sometimes with a slight indication of brown, sometimes with- 

 out any. 



The coloring of the wings is also variable, the fuscous tinge of the anterior 

 margin and the clouds on the cross-veins being sometimes very pale. The 

 cinereous tinge of the front, the brown ring on the collare, near the head, the ferrugi- 

 nous, almost orange, color of the prcescutum and the infuscated anterior margin of the 

 wing may be considered as characteristic. 



The neuration of the wings is likewise inconstant. The normal ueuration is 

 exactly like Meig. i. tab. vi. f. 4, only the first lower discal cross-vein is a little 

 nearer to the apex of the wing, (originating from the lower branch of the fork.) 

 Among my eighteen specimens, ten (eight ^ and two 9) partake of this 

 neuration. 



In three specimens, the first lower discal cross-vein is removed nearer towards 

 the base of the wing, so that the first externomedial areolel is petiolate. In one of 

 the specimens this is the case with one wing only, the same areolet on the other 

 being sessile. 



In three other specimens the discal areolet is wanting, (that is, open from 

 want of a second lower discal cross-vein.) 



In two specimens it is the cubital vein which forms the fork, and not the 

 radial, the latter originating before the fork. But in both instances the position 

 of this vein on one wing does not agree exactly with that on the other. In one 

 case the radial vein issues from the same joint with the fork. 



The great cross-vein varies in its position also. Sometimes it is opposite, 

 sometimes below the upper discal cross-vein. 



In one specimen there are three supplementary cross-veins in the cubital 

 area. 



One character which seems to be merely accidental in other species, is very 

 constant in this : it is the presence of a stump of a vein near the origin of the petiole. 

 This stump is long and distinct, and is wanting only on one wing of one of my 

 eighteen specimens. 



Fifteen $ and three 9 specimens. Washington, common early in April and 

 later; New York and Virginia Springs (nob.); Connecticut, (Mr. Norton.) 



This species seems to be allied to the European Limnobia littoralis 

 Meig. 



Pkdicia Latr. 



The characters of this genus have been mentioned in part in detailing those 

 of Amalopis. For more detaiis see Walker, Ins. Brit. Dipt. iii. p. 314. I 

 would add only to Mr. Walker's characteristics of this genus, that all the 

 tibias have two spurs at the tip and not the hind tibia; alone. 



P. albivitta. Walker, List of Dipt., etc., i. p. 37. 



Head black, front hoary; antennae pale bro.vn. Thorax pale brown, with a 

 strong silvery reflection; a brown stripe runs from the collare to the origin of 

 the wing; praescutum with three brown stripes; the intermediate one is darker 

 and capillary; halterespale. Abdomen silvery, with a row of triangular brown 



[Aug. 



