768 CHARLES PauL ALEXANDER 
erected, to include the generalized Tanyderina which have EMRE been 
placed with the Ptychopteridae. 
The immature stages of the four families of the Tipuloidea are readily 
separable. The larvae of the Tipulidae can be confused only with those 
of certain low brachycerous forms, as, for example, the Leptidae. In the 
Brachycera the mandibles work vertically and parallel to each other; 
in the Nematocera, including the Tipuloidea, they operate transversely 
or obliquely against the teeth of the mentum and the hypopharynx. 
The presence of fleshy lobes surrounding the spiracular disk is a character 
possessed by almost all Tipulidae. The larvae of a few groups of brachye- 
erous Diptera, such as certain Leptidae, Sciomyzidae, and other families, 
possess entirely similar caudal lobes but are readily recognized by the 
small and very reduced head capsule. 
The eucephalous families of the Tipuloidea may be distinguished by 
means of the characters indicated in the following keys: 
Larvae 
1. Body eucephalous, head non-retractile; amphipneustic or metapneustic.............. 
Head incomplete behind, retractile; not amphipneustic....... . TIPULIDAE (p. wi) 
2. Caudal end of body prolonged into a slender breathing ‘tube; ‘metapneustic Se 
Caudal end of body not prolonged into a breathing tube; amphipneustic. 
RHYPHIDAE (p. 787) 
3. Breathing tube stouter, non-retractile; gills large, pinnately branched; punctures of head 
multisetose; found in wet decaying wood............... TANYDERIDAE, supp. (p. 769) 
Breathing tube slender, completely or partly retractile; gills slender, cylindrical, 
unbranched; punctures of head with simple or plumose hairs; found in wet earth. 
PTYCHOPTERIDAE (p. 772) 
Pupae 
1. One of the pronotal breathing horns greatly elongated, much longer than the body, the 
other breathing horn very short, abortive. (Family PrycHoprEerRiDAg, p. 772)......2 
Breathing horns short, or, if elongated (some Tipulinae), not longer than the body 
and the difference in size not so apparent 
2. Tarsal sheaths lying side by side, parallel. . .Ptychopterinae (p. ae 
The fore tarsal sheaths overlying the middle pair, ‘the four middie and hind tarsi the 
longest parallel Ss iy-neri se ieee eee ca eee: Bittacomorphinae (p. 779) 
3. Tarsal sheaths overlying one another in pairs..................... RHYPHIDAE (p. 787) 
Tarsal sheaths lying side by side............... OU wl Reon be eee TIPULIDAE (p. 791) 
The pupae of the Tanyderidae are still unknown. 
It is possible that Bittacomorphella (page 779) has short breathing 
horns; in this case this genus would run down to couplet 3 above, but 
by the arrangement of the tarsal sheaths it runs out as indicated in 
couplet 2. 
