2G8 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
■which is protuberant and laid along the breast, extending to near the tips of the wings ; 
tho face with two parallel depressions running from between the triple tubercles and 
ending in two fossae above the frontal spines; two basal, niedio-dorsal tubercles. Thorax, 
unarmed, the prothoracic spiracle very large and raised on a curved tubercle; ineso- 
thoracic spiracle on a swelling at base of wings; front tibias stout and curved; front 
larsi reaching to tips of wings; middle tarsi to abdominal joint beyond, and hind tarsi 
to third abdominal joint beyond. Abdomen curved, with the ninth joint very small ; 
across tho middle, dorsally, each joint has a series of parallel, longitudinal, narrow, 
chitinous plates having at each extremity a spine, tho posterior one stoutest; both 
plates and spines diminishing laterally, gradually aborted on the extreme basal and 
posterior joints, and replaced on the small ninth joint by a group of four converging 
and truncate tubercles; two stouter anal spines on the subjoint and a ventral lobe 
with two short, obscurely articulate processes; each abdominal joint with a circle of 
hairs, those on lateral ridge stoutest and one-third the width of abdomen in length ; 8 
pair of abdominal spiracles (making 10 with those on thorax), the first and last pairs 
rather difficult of detection. 
Imago. — Tho perfect fly (PI. XVI, Fig. 3) is at once distinguished from the succeed- 
ing species by its broader form and long proboscis. The whole body is covered with 
long yellow or fulvous hairs. The species varies in the color of the legs and in size, 
some females being larger than the males. The species was originally described from 
Sierra County, California, and Mr. Williston informs us that he has a specimen from 
Washington Territory. Wo quote Osten Sacken's original description : 
Systoechus OREas. — Differs from S. vulgaris in the third anteunal joint being a 
little broader, tho mystax being more mixed with fulvous pile, the proboscis longer, 
tho legs darker, the wings more grayish, tho covering of pile more dense and of a 
paler shade of yellow, the ground-color less dark (when denuded), without reddish on 
tho scutellnm; on the average, the size is somewhat larger. 
Male. — The blackish-gray ground-color of the body is entirely concealed (in intact 
specimens) under a thick covering of pale yellow piie, giving the body an elongated- 
oval shape, slightly broader about the middle of tho abdomen ; face and front covered 
with a recumbent fulvous tomentum, and erect black pile; mystax mixed of both; 
some black pile on tho vertex; antennas black, third joint considerably expanded on 
its proximal half; legs black; femora densely covered with the usual appressed whit- 
ish hairs, which conceal the ground-color; tibiae reddish, but clothed with the same 
whitish pubescence ; the latter part of the tibiae is black, and on the inner side this 
color extends farther upward than externally; tarsi deep black. Wings with a 
decidedly grayish tinge, brownish-yellow at the base and in the costal a'nd first basal 
cells. Length about 10 mm (including the length of the pile at both ends of the body, 
but excluding the antennae). 
Female. — I have a single somewhat damaged specimen, which evidently belongs 
here, although it is smaller, and the femora and tibiae, except the tip, are yellowish- 
red. Length about 8 mm . 
Hal. — Webber Lake, Sierra County, California, July 22-26. Three males and one 
fcmale. None of my specimens show any reddish on the scutellum. 
Triodites mus. 
The habits of this insect in the larva state are precisely like those of 
the preceding. 
Larva (PI. XVI, Fig. 4). — So greatly resembling that of the Systwchus that it is well 
nigh impossible to separate the two with certainty. The head parts are somewhat 
broader, shorter, and less flattened, the maxillae more blunt, the labrum paler, and the 
mandibles sharper and with a smoother outer edge. The thoracic joints bulge less 
beneath and the thoracic spiracle is more sunken and less conspicuous. 
Pupa (PI. XVI, Fig. 5). — Easily distinguished from that of Systoechus in the broader 
and more bulbous head ; in the two sets of three stout spines at top being well sepa- 
rated ; in the frontal pair being stouter, each with a conspicuous bristle externally ; 
in having a single spine or tooth above these, and another much stouter, erect, re- 
curved spiue, bidentate at tip, below them or at base of tongue, which is here repre- 
sented by a cordate lobe. There is a spine on the front anterior border of each wing ; 
