854 Charles Paul Alexander 



species of Tipiila 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 les&er extent in Longurio, 

 the verticils are lacking. Tipula mainensis (fig. 125, o) 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 ocelli. 



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 so on. 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- 



