III. 

 Some Recent Insect Literature. 



IN a former review, contributed to Natural Scienxe (vol. ii., pp. 

 114-119), I noticed a new description of the ear situated in the 

 tibial joint of the front leg in long-horned grasshoppers. A summary 

 of a recent account of another insect sense-organ with an apparently 

 auditory function may also be of interest. Forty years ago ^Ir. 

 Johnston was the first to discover that the swollen basal joint of the 

 antenna in certain gnats and midges contained a complicated 

 structure, which he interpreted as an organ of hearing. Subsequent 

 observers have investigated the subject, among the more recent a 

 well-known contributor to the pages of this Review, Dr. C. H. 

 Hurst (i). The latest memoir on the subject (2) is due to the 

 labours of Mr. C. M. Child, whose work seems so exhaustive as to 

 leave but little for future investigators to learn about the structure of 

 the organ, though a considerable field remains for experimental 

 research into its various functions. 



In the insects in which this organ is most highly developed, the 

 males of certain gnats (especially MocJwnlyx) and midges (Chirono- 

 midas), the second joint of the antenna is enormously swollen and cup- 

 shaped, being somewhat concave on its distal aspect. Here, around 

 the insertion of the next succeeding joint, is a plate, called by 

 Dr. Hurst the tympanum, produced into numerous processes, in 

 connection with which are long, rod-like cells, united by means of 

 nerve-threads with large ganglion cells, which are arranged within 

 the outer wall of the swollen antennal joint, and connected with large 

 offshoots of the main nerve of the antenna. In the females of these 

 insects a similar organ is present, but in a far lower stage of develop- 

 ment, the antennal joint being not nearly so much swollen as in the 

 males. 



The most important point, perhaps, in Mr. Child's work is the 

 discovery of a homologous organ, though in a far more rudimentary 

 condition, in the corresponding antennal joint of insects of several 

 orders. The organ is shown to be present in many other genera of 

 Diptera, in Hymenoptera [Formica, Vespa, Boiiibiis), in Lepidoptera 

 {Epinephile), in Coleoptera (Melolontha), in Rhynchota {Aphis, Sirachia), 



