DIP TER A. 
429 
wings (Fig. 500) is also very peculiar. All of the longitu¬ 
dinal veins separate near the base of the wing except veins 
III a and 111 3 and veins V\ and V a . In some forms veins 
III 4 and 111 b are distinct, as shown in the figure; in others 
hey coalesce completely, so that radius is only four-branched. 
In this case there is onlv a single vein between the two 
forked veins. 
The antennae are long and slender, and are clothed with 
whorls of hairs (Fig. 501). Those of the male are longer; 
and in the species figured the two 
basal segments are clothed with scales 
like those of the Lepidoptera. Scales 
of this form occur also on the wings, 
palpi, and legs of certain species. 
Only a few of the American species 
have been described ; these have been 
Fir., tot. — Antennae of Psy- 
olaced in the genus l j sycfl 0 u(l / the c/ioda. w, antenna of male 
F 0 and the second segment of the 
early stages of none of them have same more enlarged; a an- 
J o tenna of female and the tip 
been observed. The larvae of some enlarged. 
European species inhabit cow-dung, and others live in water. 
They have a pair of spiracles at each end of the body. 
As regards the structure of their wings these flies are very distinct 
from all others. The pre-anal area, that part lying in front of vein 
VIII, presents an extremely generalized form. This is shown by the 
outline of the wing (a line drawn lengthwise of the wing through its 
centre will divide it into two similar parts), the small extent to which 
the veins coalesce, and the fact that the maximum number of veins is 
present. On the other hand, the anal area is so reduced as to be 
barely represented. The dotted line in the figure represents the 
position of what is left of the anal furrow (i.e., vein VIII). 
Family TlPULlD^E (Ti-pu'li-dae). 
The Crane-flies . 
The crane-flies are mosquito-like in form ; but they are 
usually very much larger than mosquitoes. The body is 
long and slender, the wings narrow, and the legs very 
