NORTH AMERICAN DIPTKRA. 149 



31.— Front ln-aiicli of first vein reacliinf; beyond middle of second basal cell. 



Triclioiita. 



Front branch of first vein never reaching middle of second basal cell, often 



rudimentary op 



32.— Fork of fifth vein very acute, the lower branch at its middle suddenly di- 

 verging from the upper branch Rh.Vmosia. 



Fork of fifth vein not strikingly acute, the lower branch gradually diverg- 

 ing from the upper Allodia. 



Family CULICID.^. 



l.-Proboscis short, scarcely longer than head ; metatarsi longer than next joint 



(Corethrina) Coretlira. 



Proboscis very long, always longer than head and thorax together (Culicina)..2. 



'■^■— Tip of proboscis strongly curved IVIo»'ai*rliiiia. 



Tip of proboscis straiglit 3 



3. — Palpi very short in both sexes Aodes. 



Palpi very long in both sexes, longer than proboscis, or luna. in % and short 



in 9 ; 4. 



4.— Palpi longer than proboscis in both sexes; forceps of % as long as, or shorter 



than last segment Anopheles. 



Palpi long in % very short in 9 ; forceps of % longer than last segment. 



Culex. 

 Family CHIRONOMID.E. 



1.— Flagellum of antennae in % long and thickly ciliate, plumo.se-tufted or peni- 



cillate (Chironomina) a 



Flagellum of % only short hairy, never with plume-like tufts or pencils. ..2. 



2.~AntennBe with an equal number of joints in both sexes...., 3. 



Autennfeof % 14-jointed, of 9 7-jointed ; palpi short Hydrobieiins. 



3.— Antennie 7-jointed in both sexes <'lia««inatoiiotiis. 



Antenna^. 1.5-jointed in both sexes Oecacta. 



4.— Second basal cell closed, the hind cross-vein, therefore, always distinct 5. 



Second basal cell open, hind cross-vein wholly wanting (j. 



5.— Antennae with same number of joints in both sexes Taii.ypiis. 



AutennfB with at least twice as many joints in % as in 9 I>iaineNa. 



6.— Thorax greatly arched and usually strongly produced in front; legs, par- 

 ticularly anterior pair, long and slim; third vein never furcate; Umn 

 pubescence of % antennae arranged in pIunio.se tufts.. C'iiiroiioiims. 

 Thorax moderately arched, never produced anteriorly; legs moderately long 

 and often very robust; third vein often furcate; the long pubescence 



of % antennae in pencils...., ~ 



7.— Claws of hind feet greatly unequal in length, each tarsus apparently with 

 only one claw; front femora much dilated, with a series of spines on 



anterior edge subgen. Heteroiiiyia. 



Claws of hind feet equal; front femora normal, not diffVientiatod 'from 

 *'*'^*^*"^ C'eratoi>o$;on. 



Family PSYCHODID^. 



1.— Third vein ending exactly at apex of wing Psyeiioda. 



Third vein ending below apex of wing *. o 



TKANS. AM. ENT. SOC. XIX. JUNE 1892. 



