— Costa entire, subcosta complete, ending in the costa; 

 legs with dorsal preapical bristle SCIOMYZIDAE 



22. Costa also broken at humeral cross vein; 2nd basal 7 

 and anal cells not formed (fig. 14:54;'). .. EPI1YDRIDAE 



— Costa not broken at humeral cross vein; 2nd basal 

 and anal cells complete (fig. 14:1A) 23 



23. Vibrissas present at the angle formed by the facial — 

 ridges and oral margin; prcapioal tibial bristles pres- 

 ent; transverse mesonotal suture nearly complete ... 8 



SCOPEUMATIDAE (part) 



— Vibrissae absent, only peristomial hairs or setae 

 present; preapical tibial bristles absent; transverse 

 suture not developed CANACEIDAE 



24. Hypopleuron with a vertical row of bristles (fig. 14:2A); 



4th vein (Mi) curving or bending forward, narrowing — 



the apical cell at the wing margin (fig. 14: Ik) 



SARCOPHAGEDAE 



— Hypopleuron with short fine hairs or bare; 4th vein 9 

 nearly straight, the apical cell not narrowed (fig. 14:63a) 



25 — 



25. Eyes of male not widely separated; cruciate frontal 

 bristles present; lower calypter longer than the upper 10 

 (fig. 14:2A); transverse mesonotal suture complete . 



MUSCIDAE 



— Eyes widely separated in both sexes; no cruciate 

 frontal bristles; lower calypter not longer than the 



upper; transverse suture incomplete — 



SCOPEUMATIDAE (part) 



Larvae 11 



1. Head capsule complete (figs. 14:8a; 14:16e; 14:350"), 

 or the posterior part with deep longitudinal incisions 

 (fig. 14:4A); mandibles opposed, moving in a horizontal 



or oblique plane (NEMATOCERA) 3 — 



— Head capsule incomplete or lacking (figs. 14:49c^ 

 14:54a; 14:63Z); mandibles or mouth hooks parallel, 

 moving in a vertical plane, or if their motion is obliquely 

 inward, then the head is not sharply differentiated 12 

 from the 1st thoracic segment (BRACHYCERA) .... 2 — 



2. Mandibles normally sickle-shaped, not protruding much 

 beyond apices of the we 11 -developed maxillae (fig. 13 

 14:49p); maxillary palpi distinct; dorsal part of head 

 capsule more or less developed (fig. 14:49s, t); anten- 

 nae well developed, situated on the sclerotized dorsal 

 plate; pharyngeal skeleton loosely articulated; slender — 

 metacephalic and tentorial rods present, produced into 

 thorax (fig. 14:49c) (ORTHORRHAPHA) 15 



— Mandibles short and hooklike, usually capable of 14 

 protrusion much beyond the poorly developed maxillae; 

 palpi rarely visible; no head capsule; antennae when 

 present situated on a membranous surface; pharyngeal 

 skeleton with posteriorly directed branches fused 

 anteriorly, forming a compact body (figs. 14:54a; 14:56e; 

 14:63A;, I) (CYCLORRHAPHA) 20 — 



3. Head capsule complete, not retractable within the 

 thorax (fig. 14:8a, I) 4 



— Head capsule incomplete posteriorly (fig. li:ih) and 

 more or less retractable within the thorax (figs. 14:4n, o; 

 14:5c) TIPULEDAE 



4. Head, thorax, and 1st abdominal segment fused into a 15 

 compound body division; ventral side with a median 

 row of sucker discs by which larva attaches itself 



to the surface of rocks of mountain stream beds (fig. 

 14:11a, b, d-g,i,j) BLEPHARICERIDAE 



— Head not fused with thorax and 1st abdominal segment — 

 (figs. 14:16c; 14:19a; 14:22;) 5 



5. Body flattened, thorax with 3 distinct segments; 

 abdomen with 7 pairs of large lateral pseudopods, 16 

 each supplied with several rows of concentric minute 

 hooks; antenna long, 2-branched (fig. 14: 13c) 



DEUTEROPHLEBIID AE — 



— With other characters 6 



6. Prolegs (pseudopods) absent (fig. 14:15c) 7 17 



— Prolegs present either at one or both ends of body or 



375 

 Wirth and Stone: Diptera 



on intermediate abdominal segments (firjs. 11:19a; 



14:280 9 



The 3 thoracic segments fused, forming a more or leas 

 enlarged section of the bc>.i\ distlnotl) thicket than 



the abdomen (figs. 11:11; 11: 10, ; 11: 17/) 



CLLICIDVF. 



Thorax and abdomen about equal in diameter (figs. 



14:9c; 14:18c, d,f,j, k) 8 



Thorax and abdomen with B secondary segmentation, 

 usually 2 annuli on each thoracic and 1st abdominal 

 segment and 3 for each of abdominal segments 2-7, 

 some or all of the annuli with narrow, transverse, 

 dorsal plates; respiratory openings on prothorax and 



anal segment (fig. 14:9c) PSYCHODIDAE 



Body without distinct secondary annuli or narrow dorsal 



plates; spiracles absent (fig. 14: 19A, i) 



IIELEIDAE (part) 



Prolegs present on intermediate bodv segments (fig. 



14:8A; 14:18c,/) ' 10 



Prolegs confined to anterior or posterior ends of body, 



or both 11 



Abdominal segments 1 and 2 each with a pair of ventral 

 prolegs, each provided with many small hooks; posterior 

 end of body with 2 pairs of fringed processes and a 

 terminal, bristly lobe behind the posterior spiracles 



(fig. 14: 18d, ;') DIXIDAE 



Abdominal segments 1, 2, and 3 each with ventral 

 prolegs, each with 1 or more claws; posterior abdom- 

 inal segments retractile, terminating in a long slender 



respiratory tube (fig. 14:8c, h) LIRIOPEIDAE 



Prolegs present on prothorax only; posterior part of 

 abdomen swollen and armed caudally with an adhesive 

 disc for attachment to rocks or objects in running 

 streams; maxillae usually with a fan of long hairs 



(fig. 14:19a) SIMULIIDAE 



Prolegs present on prothorax and posterior end of 

 body, or at posterior end only; body not club-shaped; 

 caudal adhesive disc absent; maxillae without long 



fanlike hairs 12 



Prothoracic and caudal spiracles present 13 



Prothoracic and caudal spiracles absent, no functional 



spiracles 14 



Prothoracic prolegs absent; long, paired, posterior 

 prolegs present; caudal end of body with 6 long fil- 

 aments; caudal spiracles paired (fig. 14:6) 



TANYDERIDAE 



Prothoracic and posterior prolegs present and unpaired; 

 caudal end of body with a single spiracle between 



2 short processes (fig. 14:436) THAUMALEIDAE 



Both anterior and posterior prolegs normally present, 

 well developed and provided with claws (figs. 14:22;'; 

 14:282), or if posterior pair is reduced, the anterior 

 pair is at least represented by patches of spinules 

 (fig. 14:28^7); body hairs not strongly developed .... 



TENDIPEDIDAE 



If both anterior and posterior prolegs are present, the 

 body segments are provided with strong spines or 

 bristles (fig. 14:39//); or if body is smooth, anterior 

 proleg may be absent and posterior proleg represented 



by a few ventral claws (fig. 14:380 



HELEIDAE (part) 



Free part of head not retractile; prolegs wanting; body 

 more or less depressed; cleft of respiratory chamber 

 transverse; integument with calcium carbonate crystals; 



pupa enclosed in last larval skin (fig. 14:45) 



STR ATIOMYHME 



Free part of head more or less retractile; prolegs pres- 

 ent, or, if absent, the body cylindrical and nearly 



circular in cross section; pupa free 16 



Apex of abdomen with 1 or 2 pairs of setigerous or 

 ciliated processes; abdominal segments each with a 

 pair of strong prolegs bearing claws (fig. 14:51) ... 17 

 Either the caudal processes or the prolegs wanting 



18 



Upper divergent pair of caudal processes as long as 

 anterior prolegs, each limb bearing 3 setae longer 



