258 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



Four somewhat similar processes (Fig. 138, A, g, and i), 

 appear upon the surface of the ninth sternum. They are 

 arranged in a transverse row, and the outer ones <j, are 

 much larger than the inner ones, and soon lengthen to 

 become the dorsal plates of the ovipositor (Fig. 138, A, 

 and B, g\ Fig. 139, o,p), while the smaller median pro- 

 cesses (i), become the inner pieces or egg-guides (Fig. 

 139, op 2 ). During these changes the ninth and tenth sterna 

 become entirely covered up and obscured, so that no traces 

 of them are present in the adult female, and the ventral 

 surface of the abdomen ends with the eighth sternum 

 (Fig. 137, i; Fig. 139, 11*). 



The terga of the ninth, tenth, and eleventh somites (Fig. 

 138, C, 9, 10, 11), persist, but their growth becomes re- 

 tarded, so that they are very much shorter in the adult 

 than those of the preceding somites, although they are of 

 about the same length in the young. 



XXIV. THE INTERNAL STRUCTURE OF THE 

 GRASSHOPPER. 



(Acridium Americanum.) 



PIN the specimen down, under water, back uppermost, 

 passing the pins through the wings, and along the sides of 

 the thorax. With a pair of fine-pointed scissors cut 

 through the integument along the dorsal surface of the 

 abdomen, and carefully separate it from the underlying 

 muscles, and pin it out at the sides. 



a. If it has not been destroyed by the incision, notice 

 the dorsal vessel, or heart, a delicate tube, which lies just 

 below the integument, on the dorsal surface of the 

 abdomen. 



