330 NEW YORK STATE MUSEUM 
KEY TO FAMILIES OF NEMATOCEROUS DIPTERA 
Larvae 
1 Mandibles opposed, with the jaws movy- 
ing in a horizontal plane; when the 
mouth parts are rudimentary, the larva 
has 13 segments and is peripneustic’ (2)............. Nematocera 
Mandibles parallel, their motion in a verti- 
eal plane; if the motion is obliquely 
inward, then the head is not sharply 
differentiated from the first thoracic 
Seoilent, 1:7: esse Lees lat Ss eee Brachycera 
2 Larva with fully differentiated head, non- 
retractile, which contains the first gan- 
glion and sometimes the eyes, perip- 
neustic or amphipneustic,? with breath- 
ime tube.er trachea lols. us <a see CG) chats ie Tribe Hucephala 
Larva with enly a “jaw capsule” (Kie- 
£er, kapsell)'> sc icon Satie cee oe ee uae (14) 
3 Terrestrial forms, living in the earth, in 
rubbish, under bark, or in fungi....(4) 
AGMALIC= OF SCMMACUALIC. ce. kkk ae akiewe (6) 
4 Larvae without thoracic prolegs....... (5) 
With thoracic prolegs. Living under bark........... Ceratopogon 
5 Body bristly; head usually with eyes... 5: 22.5. see Bibionidae 
Body not bristly, head usually without 
CHER = Nom ens ce oye cos Mice tataks' suas rok de. See Mycetophilidae 
6 Prolegs at least on fourth and fifth seg- 
ments (i. e. on first two abdominals) (7) 
No prolegs on these segments......... (8) 
7 Spiracles on the first and last segments, 
with tracheal gills, and a very long 
membranous breathing tube.......ccl.+. snes se Ptychopterinae 
No long respiratory tube; larva swimming 
in @ U-SRape. 26 cecc swan tte ccs bee ne ener ee ce Dixidae 
8 Body flattened, onisciform, and usually 
with isuckers wndernesth, : 56.0 cece (9) 
Body more or less cylindric, without suck- 
ers on the intermediate segments. ..(10) 
9 The segments alternating small and large, 
the outline of the body, serrate.- Liv- 
ing in. Fapid Bowing ‘Streams... 7... 5s. se eeae Blepharoceridae 
The segments gradually larger at the mid- 
dle of the body, becoming smaller 
again toward the posterior CNG. ....0 :Jo.4..0sne see Psychodidae 
10 YVith. thoracie ‘proleosy vous «see ce (13) 
Waithbout, thoracte prolegar ype ses (11) 
*Spiracles confined to the median segments. The Chironomidae usually . 
have jaws which move in oblique planes. 
*Spiracles confined to the first and last segments. 
