192 THE CANADIAN ENTOMOLOGIST, 



covering the entire width of the connexivum, save for a narrow stripe at 

 tlie external edge. This band begins about two-thirds of the way up the 

 last connexival segment, and is lost under the edge of the metasternum. 

 On each of abdominal segments 2 to 6 there is visible in this sericeous 

 stripe an oval stigma from which arise tracheae that lead into the main 

 respiratory system. The spiracles of the first segment are not visible 

 without dissection, and lie in the membranous portion under the 

 metasternal episterna. The main system has its origin in the two strap- 

 like appendages issuing from the dorsum of the 5th abdominal segment, 

 which are evidently the highly specialized 7th abdominal ring.^ These 

 are each covered at the base by a pilose flap which extends from the 

 segment, and between them lie the genitalia. Near the base and below 

 the outer edge of each of the appendages is a deep-sunk orifice in which 

 lies the great spiracle from which springs the large tracheal trunk of the 

 main system. Each of these large stem-trachcc^ goes straight up into the 

 thoracic region, each connecting with the other and with the seven 

 abdominal and three (sec. Schiodte) thoracic stigmata by branches at 

 intervals. The dorsum is covered with short pile, and as it is somewhat 

 hollowed beneath the hemelytra, is apparently employed as a reservoir for 

 storing air. When the bug is at the surface, the end of the abdomen and 

 the hemelytra separate, the hairy ends of the strap-like appendages being 

 visible just under the edge of the membrane, and the air enters here. 



The nymphal respiratory apparatus is quite different. In place of 

 the sericeous band, the entire abdomen is thickly covered with long pile ; 

 and it appears bright and silvery in the water, and rounded out from the 

 great quantity of air it carries. The connexival spiracles, of which there 

 is one at each segment, are not large, and connect by tracheae with the 

 main respiratory system. There is a pair of very large spiracles in the 

 cleft sixth abdominal segment, one on each side, from which the main 

 tracheJB rise. The metasternal episterna are produced into long, narrow 

 plates, fringed with long hairs, extending over the first, second and half 

 the third abdominal segments. According to Dr. Sharp,' Joanny Martin 

 is of the opinion that these plates are for respiratory purposes. It is 

 possible that they may be used for the storage of air, or perhaps as a 

 means of reducing the quantity held by the pile, by exercising pressure to 



7. Dufour in M^m. Soc. Ac. Sci. Liege, 186, p. 197, expresses the guarded 

 opinion that the strap-like appendages of BeJostonia ( = Amorgius) indicum are 

 respiratory in their function. 



8. Cambridge Natural History, Insects, Part II, p. 567. 



