1012 CHARLES Paut ALEXANDER 
The large, fleshy larvae occur beneath or among drift at or near th 
margins of streams. They are usually abundant under saturated decay 
ing leaves or under tussocks of grass at the edge of the water. ‘The 
are entirely herbivorous, feeding on diatoms, decaying plant tissues 
and other vegetable matter. The larvae are readily distinguished fro 
all other species of the genus by the small spiracles and the bifid or sph 
lobes surrounding the spiracular disk. Pupation takes place in the muc 
or earth at the water’s edge. Malloch’s Tipula sp. 2 (1915-17b : 200 
201) seems to refer to T’. abdominalis, but the mouth parts of his speci 
mens do not seem to be normal. 
Larva.— Length, 55-65 mm. 
Diameter, 7.5-10 mm. 
Coloration pale grayish brown; anterior end darker. 
Form stout, terete, thin-skinned. Posterior ring of abdominal segment, both above an 
below, with a naked transverse welt, which bears the setae; this welt very protuberant ¢ 
its lateral ends, almost like a pair of prolegs. Skin naked, except for a microscopic dottin 
and the rather short, delicate setae. Chaetotaxy as follows: tergites, on welt at about mig 
length, a transverse row of eight setae, the middle pair of each half closely approximated 
pleurites with a, single seta opposite basal ring, and two opposite posterior ring, arrange 
one behind the other; sternites with four pairs of setae on welts, anterior middle pair clos¢ 
together than posterior lateral pair. Spiracular disk (Plate XCVII, 537) moderately larg 
flattened, truncated, surrounded by six deeply bifid and irregular lobes; ventral lobes elom 
gate, with a blunt basal branch bearing two setae; posterior branch longer, indistinct 
bifid at tip and with a few setae and several hairs; lateral lobes deeply bifid, the ventr: 
one armed with lateral setae; dorsal lobes small, simple; inner faces of dorsal and later 
lobes with a narrow dark brown stripe, ventral lobes with two narrow, usually indistin 
lines, these markings broadest and darkest on dorsal lobes. Spiracles very small, circula 
separated by a distance about equal to four times diameter of one. Anal gills six, long ar 
slender, the middle one on either side a little shorter than the others. Pleural region 
penultimate segment of body with a blunt setiferous tubercle. 
Head capsule and mouth parts about as in genus. Mentum (Plate XCVIL, 536) broad 
transverse, anterior margin with seven to nine teeth, in the latter case the outermost tee 
very indistinctly separated from the sublateral teeth. Hypopharynx broad, anterior marg 
with teeth very indistinct. 
Sey 
Pupa.— Length of cast pupal asta “about 35 mm. 
Pronotal breathing horns short, straight, cylindrical; apex short, and but little if at 
expanded. Details of mouth parts as in other species of genus. Wing sheaths endi 
before apex of second abdominal segment. Leg sheaths extending to about opposite eé 
of third abdominal segment; fore tarsi the shortest, hind tarsi the longest, ends of tar 
sheath thus forming a broad, inverted U-shaped notch. 
Abdominal armature generally weak. Tergites (Plate XCVII, 538) with subterminal rij} 
broken, consisting of an anterior median pair of large spines, laterad of which are two 
