854 CHARLES PauL ALEXANDER 
species of Tipula and some species of Nephrotoma have the segments 
deeply incised on the under face, producing a serrated appearance. In 
Stygeropis (fig. 125, n) and Holorusia, and to a lesser extent in Longurio, 
the verticils are lacking. Tipula mainensis (fig. 125, 0) is a typical Tipula 
and illustrates this verticillate condition. 
The eyes 
On either side of the head, in all crane-flies, are the large compound 
eyes, made up of numerous facets, or ommatidia. In generalized forms 
the facets are large and coarse, so that the eye presents a coarsely granu- 
lated appearance; in other species the ommatidia are so small and abundant 
that the surface of the eye appears very smooth and regular. In most 
species of Tipulidae the eyes are separated by a narrow strip of the front 
(dichoptic), but in the males of some they are contiguous (holoptic) or 
nearly so, as in certain species of Rhipidia and allied groups. In some 
species of Erioptera (Erioptera macrophthalma, E. vespertina, E. nyctops, 
and others) the eyes of the males are much larger than those of the 
females and are contiguous beneath. 
In most genera the eyes are large and extend backward onto the caudal 
part of the head. In Trichocera and Ischnothrix the vertex bears three 
simple eyes, or ocellz. 
The thorax 
The thorax is the second region of the body and lies between the head 
and the abdomen. This part of the body bears the legs, and, when they 
are present, the wings also. It is divisible into three subregions, as 
follows: the prothorax, or first segment, which bears the fore legs; the 
mesothorax, or second segment, which bears the middle legs and the 
wings; and the metathorax, or third segment, which bears the hind legs 
and the halteres. The upper, or dorsal, sclerites of these subregions 
are called the tergites, the notum, or the dorsum; the lateral sclerites, 
those on the sides of the body, are the pleura, or pleurites; those on the 
lower, or ventral, parts of the body are the sternites, or sternum. Each 
subregion has its own terminology, the prothorax having its pronotum, 
propleurites, and prosternum, the mesothorax its mesonotum, meso- 
pleurites, and mesosternum, and soon. The legs borne by these respective 
segments likewise have the corresponding prefix applied to their parts — 
as the precoxa (or fore coxa), the mesocoxa (or middle coxa), the pre- 
