568 HEMIPTERA CHAP. 



narrow area ; in this respect it differs widely from Notonecta, 

 which possesses an extremely large occipital foramen, and the 

 head of which possesses bub little freedom of movement. The 

 extremely short proboscis is more or less retractile, and therefore 

 frequently appears absent. A second British genus consists of a 

 single species, Sigara minutissima. These Insects, unlike Noto- 

 nccta, are quite at home beneath the water, where they scurry 

 about with extreme rapidity, and occur sometimes in enormous 

 numbers. In Mexico the eggs of Corixa americana and of C. 



C3O 



fe/iwrata are used as food, and are said to be very nice. The 

 Insects themselves are used as food in both Mexico and Egypt. 

 The species of this family can make a noise beneath the water by 

 rubbing the front feet against the proboscis. 1 The males have a 

 very complex asymmetry of the terminal segments, and in some 

 species possess on one side of the dorsal surface a curious asym- 

 metrical organ consisting of rows of very closely-packed, in- 

 tensely black, comb-like plates, called by Buchanan White a 

 strigil. This organ seems to be similar to the peculiar structures 

 found on the terminal segments of certain species of Scutellerides. 



Sub-Order II. HOMOPTERA.- 



Fam. 1. Cicadidae. Head with three ocelli, placed triangularly 

 on the summit betu'ccn the compound eyes ; antennae consisting 

 of a short basal joint, surmounted by a hair-like process divided into 

 about Jive segments. Front femora more or less thick, armed with 

 teeth. Peduncle (or basal joints) of antennae without sensitive 

 organs. This important family consists chiefly of large Insects, 

 few being as small as one inch across the expanded wings, while 

 in some the expanse is as much as seven inches. As a rule 

 the four wings are transparent and shining, with the nervures 

 remarkably distinct and dark coloured : but there are numerous 

 forms where the whole creature, including the wings, is highly 

 pigmented in a showy manner ; frequently in black and yellow. 

 Cicadas are said to be without any special protection, and to be 

 destroyed in considerable numbers by birds and other animals. 

 The body is broad and robust, and is never shaped into the 

 extravagant forms we meet with in some of the other families of 

 Homoptera. Cicadidae are almost confined to the warmer regions 



1 See Carpenter, Irish Naturalist, iv. 1895, p. 59. 

 2 See remarks on pp. 543, 544. 



