i8o NATURAL SCIENCE. Sept.. 



in Neuroptera (Gibelbula), in Pianipeunia (Sialis, Panovpa), and in 

 Tricoptera {Phryganea). Only in the Orthoptera {Phasgonuya and 

 Stenobothvus) which he examined did Mr. Child fail to find the organ. 

 The presence of the structure in different stages of development in so 

 many different kinds of insects is of considerable interest, as it throws 

 light on the steps by which it has reached the high grade attained in 

 the male gnats and midges. Mr. Child believes, with much reason, 

 that the advance in structure corresponds to an advance in function, 

 from the apprehension of mere touch-sensations to that of definite 

 sound vibrations. There must indeed be a stage at which the former 

 are merged into the latter. In the gnats and midges, where the 

 organ is specially developed in the males, it has doubtless a special 

 sexual function. Dr. Hurst and Mr. Child both point out that 

 experiments have shown the hairs on the shaft of the antennae of a 

 male gnat to vibrate to the same note which is known to be produced 

 by membranes connected with the thoracic spiracles in the female. 

 The " ear " in the male's antenna, therefore, enables him to ascertain 

 the proximity and direction of a mate, for the hairs vibrate most 

 readily when the path of the sound cuts them at right angles — that 

 is, when the sound comes from the direction towards which the 

 antenna points. 



Here, then, we have an instance of the male insect hearing a 

 sound produced by the female. It is well known that in most insects 

 which produce sounds, the musical performance is characteristic of 

 the male ; and an old writer has been so ungallant as to congratulate 

 the cicads upon having silent wives. Some observations on shrill, 

 chirping notes produced by small water-bugs of the genus Covixa were 

 brought to my own notice last year. Finding that although the 

 sounds had been previously heard by several naturalists, both in 

 Great Britain and on the Continent, there had apparently been no 

 explanation of them offered beyond the fact that the front feet were 

 drawn across the face, I examined those limbs in both sexes of 

 several species. This study (3) showed the presence, in the males 

 only, of a row of extremely fine pegs, or teeth, on the flattened tarsal 

 joint, and it seems evident that these form a musical " comb " which 

 sounds when the foot is rapidly drawn across the sharp edge of the 

 face. Last year a French observer, M. Ch. Bruyant (4) heard 

 similar notes from Sigava, a minute relation of the CorixiE, and 

 described a similar comb-like instrument as their cause. 



While such insects call each other by a " song," others— the 

 humble glow-worm a well-known example — attract by a shining light. 

 An interesting paper by Herr P. Schmidt (5) gives some particulars 

 of luminous midges (Chironomidae) which have been observed in 

 various parts of Russia, in Pomerania, in Persia and Turkestan, the 

 earliest quoted notice of the phenomenon being a century old. In 

 certain localities the shining midges are said to be so numerous as to 

 make entire shrubs glow with their light. These insects proved. 



