102 ZOOLOGY. 



steps in its metamorphosis into a pupa and adult. The 

 knowledge thus acquired will be worth more to the student 

 than a volume of descriptions. 



On making a superficial examination of the locust (Valoptenus 

 femur-rubrum), its body will be seen to consist of an external crust, 

 or thick, hard integument, protecting the soft parts •within. This 

 integument is at intervals segmented or jointed, the segments more 

 or less like rings. These segments are most simple and easily compre- 

 hended in the abdomen or hind-body, which is composed of ten of 

 them. On examining the abdomen, it will be found that the rincrs 

 are quite perfect, and that each segment may be divided into an 

 upper (tergal), a lateral (pleural), and an under (sternal) portion or 

 arc (Fig. 127, A). 



As these parts are less complicated in the abdomen, we will first 

 study this region of the body, and then examine the more complex 

 thorax and head. The abdomen is a little over half as long as the 

 body, the tergum extending far down on the side and merging into 

 the pleurum without any suture or seam. The pleurum is indicated 

 by the row of spiracles, which will be noticed further on. The 

 sternum forms the ventral side of the abdomen, and meets the 

 pleurum on the side of the body. 



Jn the female (Fig. 127, />), the abdomen tapers somewhat toward 

 the end of the body, to which are appended the two pairs of stout, 

 hooked spines, forming the ovipositor (Fig. 127, B, r, r'). The vent 

 is situated above the upper and larger pair, and the external open- 

 ing of the oviduct, which is situated between the smaller and lower 

 pair of spines, and is bounded on the ventral side by a movable tri- 

 angular acute flap, the egg-guide (Fig. 127, B. eg). 



The thorax, as seen in Fig. 127, consists of three segments, called 

 the prothorax, mesothorax, and metathorax, or fore, middle, and 

 hind thoracic rings. They each btar a pair of legs, and the two 

 hinder each a pair of wings. The upper portion of the middle and 

 hind segments, owing to the presence of wings and the necessity of 

 freedom of movement to the muscles of flight, are divided or differ- 

 entiated into two pieces, the scutum and scutdlum* (Fig. 127), the 

 former the larger, extending across the back, and the sen tell um a 

 smaller, central, shield like piece. The pronotum, or what is usually 

 in the bookfi called the prothorax, represents either the scutum or 



* There are in many insects, as in many Lepidoptera and Hymenop- 

 tera and the Neuroptera, four tergal pieces, i.e., praescutum, scutum, 

 BCutellum, and postscutellum, the first and fourth pieces being usu- 

 ally very small and often obsolete. 



