372 SUMMARY or CURRENT RESEARCHES RELATING TO 



Arthropoda. 

 a. Insecta. 



Corsebus bifasciatus,* — A. Laboulbene discusses the sexual 

 differences of this Coleopteron, and tbe characters of its so-called 

 eggs. He finds that the male has been mistaken for the female, and 

 that the oviform bodies are true Acari, in the body of which develop- 

 ing ova were to be detected ; the oviform body, then, is nothing but 

 the globular abdomen of the mite, which is swollen out into a vesicle 

 more like that of Termites or Pulex penetrans than anything which is 

 found in any other acarid of the same family. 



Mouth Parts of Diptera.f — The descriptive part of H. J. Hansen's 

 work is preceded by a full historical account of the work of others, 

 from Swammerdam to the recent writers, such as Dimmock, Becher, 

 Meinert and Krapelin. It is written in Danish, with a Latin 

 abstract, or " Conspectus systematicus," of the chief results, and the 

 explanations of the plates are both in Danish and Latin. 



Mouth-Organs of Lepidoptera.J — P. Kirbach, after an account of 

 what is generally known as to the structure of the mouth-organs of 

 insects in general, and of Lepidoptera in particular, proceeds to his 

 own observations. With regard to the histological structure of the pro- 

 boscis, he points out that the lowest portion is distinctly lamellar, and 

 consists of thin transparent layers, while the upper portion has 

 chitinous bodies deposited in its otherwise homogeneous ground 

 substance ; these bodies are set at pretty regular distances, and always 

 have their broadest surface turned outwards. True scales, completely 

 analogous to those of the wings and other parts of the body, are to be 

 found on the maxillae of many moths and of some butterflies. 



The author has been interested in the formation of the rod-like 

 bodies found within the closed sucking canal ; he was at first inclined 

 to ascribe to them a gustatory function, but this was opposed by their 

 possession of a chitinous membrane, and by the presence of true gus- 

 tatory organs within the mouth. Nor can they have an olfactory 

 function, but must rather be tactile organs which test the fluidity and 

 viscidity of the fluid — a not unimportant function, as the quantity of 

 saliva that has to be mixed with the food depends on the degree of 

 its viscidity. 



In answer to the very interesting question as to how the sucking 

 canal is formed, the author points out that, owing to the close apposi- 

 tion of the two maxillae, a tube is formed through the whole length of 

 the proboscis, and this is nearly circular. How are the maxillae kept 

 closely united and the canal so closed as to be air-tight without 

 restraining the powers of movement of the proboscis ? A series of 

 closely-applied, thin, chitinous plates are inserted into the chitinous 

 ridges which are placed near the sides of the groove ; these plates are 



* Comptes Rendus, xcviii. (1884) pp. 539-41. 



t H. J. Hansen, ' Fabrica Oris Dipterorum,' part 1 (Tabanidse, BombyliidaB, 

 Asilidss, Thereva, Midas, Apiocera), 8vo, Copenhagen, 1883, 250 pp. and 5 pis. 

 See Amer. Natural., xviii. (1884) p. 274. 



X Arch. f. Naturg., 1. (1884) pp. 78-119 (2 pis.). 



