108 THE CAUSES WHICH PliOPAGATE 



Species preys on grasshoi^pers, which it carries from bush to 

 bush. This alar stridor^ which we shall again notice in the 

 butterflies and crickets^ appears due to serration of a wing-vein. 



STRIDULATION OF THE HEMIPTERA. 



As we have musical fishes, whose drumming in the deep 

 river or ocean bed maybe gave colour to the ancient tales 

 of the mermaiden, so there are musical water-bugs [Ilijdro- 

 corisida), which utter a startling voice beneath the calm lake 

 or inky pool, over-starred with white water-lily and ranunculus. 

 When pondering on a remark by L. Frischs, that the male 

 Broad Water Bug, a species which from a rude accompanying 

 figure of nymph and imago appeared to be the common Naucoris 

 cimicoides, L., produces with its neck a fiddling noise like 

 the Longhorn Beetles, I dubiously experimented on some 

 individuals, late the tenants of a willow-hung, rain-water pool, 

 and finding a faint sound like the scratching of a needle-point 

 would at times ensue when the overlap of the delicate tense 

 and pellucid tergum of the prothorax was nodded to and fro 

 and slightly pressed on the upper surface of the mesothorax, was 

 led to examine the lateral front angles of the latter, where I 

 detected a minute lima of the/ shape, thickly set with striae. 

 I next investigated another member of the rapacious Nejnda, 

 a handsome ruddy-winged Water Scorpion, very kindly sent 

 me for the purpose by the author of the "British Hemiptera,^^ 

 and finding the edge of the prothorax, if depressed and worked 

 over the mesothorax, elicited an ominous sharp click or crackle, 

 proceeded to inspect the superior lateral angles, and here dis- 

 covered two faint, triangular, rounded, striated surfaces, resembling 

 in all respects but position the lima of many Longicorns. 



In Corixa Panzeri, Fieb., a little, light-oared bug that basks 

 on its subaqueous sand-flats like a flounder, they are again seen 

 here f shaped and elongate. Corixa striata, Cm-., its congener, 

 has been recorded performing in a parlour aquarium. At the 

 meeting of the British Association in 1845, Mr. Ball noticed the 

 fact of one of the Notonectidae, Corixa striata, Cur., emitting loud 

 and powerful sounds, somewhat like those of a cricket. " These 

 sounds were given out while the animal was about two inches 

 and a half under water, and so loudly as to be distinctly audille 



