Pomona College, Claremont, California 71 
ring yellow surrounded by an outer dusky margin. Anal gills fleshy and protuberant 
as a blunt ring surrounding the anus (fig. 10). 
Head-capsule (fig. 2) of the compact, massive type of the Limnobiini; prefrontal 
sclerite (fig. 3) large and distinct; the sclerite broad with the sides subparallel to 
about midlength, thence tapering gradually to the tip which is entire; there are two 
or three punctures at the margin before midlength. Interno-lateral plates narrow, a 
little longer than the prefrons; externo-lateral plates very broad, thin and flattened 
with the posterior margin very obtuse and the inner ventral portions continuous with 
the mental plate. Labrum (fig. 3) very broad and extensive, flattened, pale in color, 
the anterior margin with about two sense-organs. Mentum (fig. +) deeply split 
behind but not completely divided, the anterior margin with three primary teeth that 
are subequal in size or the middle one a little smaller; a much reduced lateral tooth 
on either side. Prementum smaller than the hypopharynx, in outline roughly oval or 
semicircular with the two labial palpi surrounded by hairs at the base. Hypopharynx 
(fig. 5) consisting of two chitinized arms that are contiguous but not fused medially, 
the concavity between them filled with a rounded cushion that is covered with tubercles 
arranged in more or less distinct oblique parallel rows. Antenne (fig. 6) two-seg- 
mented, the basal segment cylindrical with an auditory plate on the face at beyond 
midlength; apical segment long and slender, in length but slightly less than the basal 
segment, tapering gradually to the bluntly rounded apex. Mandibles (fig. 7) simple 
with the teeth blunt; apical point longer than the lateral teeth; dorsal tooth single, 
broad, very flattened and obtusely pointed; ventral teeth two, a little smaller than 
the dorsal tooth. Maxille (fig. 2) of a generalized structure, the cardines distinct and 
feebly chitinized; distal lobes of the organ consisting of a subequal inner and outer 
lobe; the outer lobe with an abundance of long, delicate hairs and bearing a few 
sensory papille including one larger palpiform organ. 
Pupa—tLengh, 9.1-12.8 mm. 
Width, d.-s., 1.6-1.8 mm. 
Depth, d.-v., 1.6-1.9 mm. 
Thoracic dorsum shiny light brown; in very old pupe the color is much darker, 
but still retains a much brighter color than the leg and wing-sheaths; abdomen pale 
becoming darker in age, especially on the pleura. 
Cephalic crest (fig. 13) low and depressed, inconspicuous, lying between the 
antennal bases which extend beyond it; there are four small setigerous lobes, the 
larger pair of which are posterior in position. Front between the eyes broad, sub- 
parallel. Two blunt tubercles on either side of the forehead. Eyes large, with coarse 
ommatidia. Labrum semicircular in outline, tumid. Labial lobes large, oval, con- 
tiguous with one another, at the tip of the labrum. Maxillary palpi moderately long 
and slender, nearly straight, gradually narrowed to the tip which ends opposite the 
knee-joint of the fore legs. Antenne with the basal segments separated only by the 
cephalic crest, the sheaths ending about opposite or a little before the lateral angle 
of the thorax. 
Pronotal breathing-horns (fig. 14) very small, almost microscopic; when viewed 
from the dorsal aspect appearing as tiny triangular tubercles. Mesonotum moderately 
convex, unarmed, the V-shaped suture distinct; a few sete on the mesonotum, including 
one near the end of each scutal lobe. Woing-sheaths rather short, but narrow, ending 
about opposite midlength of the third abdominal segment. Leg-sheaths ending opposite 
