METAZOA INSECTA. 421 



zontally ; the antennae are concealed from view, being 

 hidden under the eyes. The jointed sucking tube ex- 

 tends backward and consists of the two parts of the sec- 

 ond pair of maxillae united. Within this tube are the 

 mandibles and first pair of maxillae, which are sharp 

 bristle-like organs used for piercing the flesh of animals. 

 The legs are greatly modified ; the forward pair are pro- 

 vided with claws, one jaw of which closes upon the other 

 like the blade of a knife upon its handle. These legs are 

 strong enough to catch small fish and to hold them, while 

 the sucking tube draws the blood of the animal. The 

 hind legs are powerful swimming organs. The anterior 

 pair of wings exhibit the peculiar structure of the typical 

 Hemipterous wing, having a horny basal portion, while 

 the remaining part is membranous ; hence the name 

 Hemiptera, meaning half and wing. The posterior wings 

 are membranous throughout, and are useful flying or- 

 gans ; both pairs of wings lie flat on the body, their tips 

 crossing. When wings are present in these water insects, 

 they aid in seeking out a favorable habitat for the dis- 

 semination of the species ; Belostoma is capable of long 

 sustained flights, 1 and Zaitha (Nos. 1041, 1042) resem- 

 bles Belostoma. Zaitha has, however, the habit of fasten- 

 ing its eggs on its back (No. 1041). According to Slater, 2 

 it is the male that carries the eggs, and the ovipositor of 

 the female is too short to place the eggs on her back, as 

 has been supposed. The wing covers are concealed, as 

 seen in No. 1041, so that these organs are useless for 

 locomotion until the youn'g are hatched. 



The spiracles in Belostoma and Zaitha are apparently 

 closed, but they have valvular openings which admit the 

 air. 



Ranatra (No. 1043) has besides the spiracles a pair of 

 respiratory tubes at the end of the abdomen. This insect 



1 Dimmock, Ann. Rep. Fish and Game Comm. Mass., 1886, p. 70. 

 1 Amer. Nat., XXXIII, 1899. 



