•76 DirTERA or north AMERICxN.. [part IV. 



vein ; a smaller one at the tip of the second longitudinal vein ; 

 cross-veins infuscated, as well as the tips of all the other longi- 

 tudinal veins. Subcostal cross-vein at the tip of the auxiliary 

 vein, which is distinctly beyond the middle of the prtefurca ; 

 marginal cross-vein very near the tip of the first longitudinal 

 vein ; second basal cell a little shorter than the first. 

 Hah. New York ; two female specimens. 



19. D. defusicla 0. S. % and J. — Fusco-cinerea,thoracevitti3tribus 

 nigro-fuscis, intermedia duplice ; pedes nigro-fusci, femora apicem versus 

 annulo albido: alse in cellulis omnibus seriatim fusco-maculatse et punc- 

 tatse ; veni, auxiliari pone prsefurcje iuitium modice extensa. 



Brownisli-gray, thorax with three brown stripes, the intermediate double ; 

 feet blackisli-brown, femora witli a whitish ring towards the apex ; wings 

 with brown spots and dots arranged in rows in all the cells ; the aux- 

 iliary vein is somewhat prolonged beyond the origin of the prsefurca. 

 Long. Corp. 0.35 — 0.4. 



Syx. Dlcranompa dcfunc/a 0. Sacked, Proc. Ac. Nat. Sc. Phil. 1859, p. 213. 



Head cinereous, front and vertex almost black in the middle ; 

 rostrum, palpi, and antenniB fuscous ; joints of the flagellum sub- 

 globular, with short verticils. Thorax cinereous with three brown 

 stripes, the intermediate one divided in two by a pale longitudinal 

 line ; pleura3 variegated with brown ; halteres pale with black 

 knobs ; coxce cinereous, feet brown, base of the femora tawny ; 

 a very distinct whitish ring at a distance equal to its own width, 

 from the tip of the femora. Abdomen blackish cinereous ; 

 posterior margins of the segments paler ; genitals pale. Wings 

 with a grayish tinge, spotted with blackish-brown ; subcostal cell 

 infuscated at four intervals ; several spots, forming a short trans- 

 verse band, along the central cross-veins ; series of small, round 

 dots along the middle of the cells ; a larger spot at the tip of the 

 seventh longitudinal vein ; stigma square. 



Hab. Washington, D. C. ; Trenton Falls ; Maine ; Canada. 

 I have often found it alighting on rocks and stones over which a 

 thin sheet of water was running. 



The forceps of this species (Tab. Ill, fig. 1 and 1«) has more 

 elongated, slender lobes than the typical Dicrayiomyise ; no rostri- 

 form horny appendage is apparent. The ungues are large and 

 have several notches on the under side, instead of the teeth, 

 which characterize the Limnobina. The excision on the under 



