228 DIPTERA 
tomentum, prothorax visible from above, the prosternum long, but a little shorter than the mesosternum, 
flared out around the base of the cox: and sometimes medially sulcate; bristles strong, one or more 
humeral, one posthumeral, five or more dorsocentral one or two notopleural, one or no supra- 
alar, one postalar, two scutellar bristles, acrostichals biseriate or wanting, sometimes the disk or the - 
margin of the scutellum setulose and sometimes there are alternating setulz in the dorsocentral TOWs; 
metapleurz with a group of upturned hairs, prosternum more or less hairy. Abdomen tomentose or - 
pruinose, of the male the last two segments are small and support the forward-directed epipygium, which - E | 
comprises a hood-shaped ventral piece terminated by the geniculate slender penis and bearing the 
circular convex lateral valves, to which are articulated the various-shaped and complicated upper ; 
valves. Legs slender and elongate, front coxa about one-half their femora in length, more orless - 
setose or hairy along their front surface, the front femora sometimes a little thicker basally and variously - 
provided with setulz, preapical femoral bristles or setulz» sometimes developed, sometimes a character- - 
istic oblique comb of setulz on inner side of front femora just before the knee, tibi without apical 
spurs, the hind tibiz sometimes bearing setze, pulvilli small, empodium narrow and about as long as 
the claws except in Bergensíammia where it is practically absent. Wings cuneiform, no anal angle, the 
costa strong around the entire margin, costal hairs long, costal setulze more or less developed, in Eucelidia 
the setulz are prominent, humeral crossvein distinct, auxiliary vein entire, gently curving into the costa, 
first vein terminating near the middle of the wing, stigma prominent or poorly developed, marginal - 
cell elongate, third vein forked, the upper branch sometimes connected with the second vein byan 
adventitious crossvein, in which case there are three submarginal cells, discal cell complete, pointed or 
blunt at its apex, emitting three posterior veins, the second posterior cell sessile or acute at its base, — 
second basal cell small the fourth vein starting beyond the base of the anal cell with an abrupt bend, - 
anal and second basal cells coextensive, the anal crossvein recurved or reflexed and continuing uninter- 
ruptedly under the anal cell, anal vein distinct from the anal cell, or wanting, marginal cilia usually 
short. 
This group of the EmPidide was subdivided by Mik in 1881 into ten genera. In doing this Mik 
was ahead of his time, for even yet many of his characterizations are not considered to have generic 
value. Two of his groups, based on the structure of the face and cheeks, are here preserved as of 
generic rank, the remainder being considered as subgenera of the primary two. — Mik's distinctions have 
not always been correlated in the North Americal species, nor in the subsequently discovered European 
ones, but in the main his selection of such characters as the structure of the cheeks and of the epistome, 
the formation of the empodium and the variations in chzetotaxy, showed a keen appreciation of characters 
hitherto neglected. In 1918 Engel published an extended critical review of the subgenera and species 
of Clinocera under the name Af/alanta. 
The species of C/inocera are very distinctive in appearance. The elongate thorax with olive-brown 
back and pruinose sides, the long slender black legs, short thick proboscis and cuneate wings, which are 
often spotted, are characteristic of the Clinocerans. Further distinctions exist in the furcate third vein, 
the small second basal cell and the rounded anal cell. The species are all found about damp woods, 
flying along water-courses or sometimes about ponds. They are boreal, occurring mainly in the North, 
in mountainous regions, some even appearing with the melting of the snow. They rarely occur in 
swarms, but while they are not rare insects, they are not easily captured, for they remain close to the 
water, fearlessly frequenting waterfalls, or running over the wet stones or even on the surface of the 
water, and thus they can be taken in the net only with difficulty. As adaptations to this life there have 
been developed the peculiar tomentose body covering, the dense pubescence of the eyes, the long 
legs and wings and the strange sensitive hairs and empodium at the apex of the tarsi. 
