ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
35 
life-liistory — of L. pratensis and L. hypotrophica at least — thus occupies 
three years. 
Halteres of Diptera.* * * § — Herr E. Weinland has a long and detailed 
paper on the “ balancers ” of Diptera. The balancer is modified from a 
hindwing and has in its interior canals, which correspond to the veins 
of a wing ; it is of no use as an organ of flight. It is capable of a large 
number of various movements which are rendered possible by a second 
joint which is to be found at its base, and in which the proper thoracic 
muscles take no part. It can bring about differences in the direction 
of the flight of an Insect in the vertical plane ; if the balancers act 
unequally there is a change in direction. 
The sensory organs formed of variously constructed papillae which 
are found at the base of the halteres are the means by which movements 
are perceived. The movement of the organs when the insect is not 
flying has for its object the preservation of the equilibrium of the body. 
A new Cecidomyia.j — Dr. F. Thomas describes the life of Cecido- 
myia pseudococcus sp. n., which has this special interest, that the larva is 
not errant, but keeps to one position on the leaf of Salix caprect and yet 
forms no gall. The absence of a gall may be due to some constitutional 
peculiarity of the species, e. g. in its secretion, but it is more probably 
an illustration of the general fact that galls are formed only on leaves 
which are still growing, for this species is too slow in developing to be 
able to attack the young willow leaves. 
Herr E. H. Riibsaamen J gives a careful description of the pupa and 
imago of this new species. 
Host of Hypoderma lineata.§ — Prof. F. Brauer publishes the dis- 
covery which the late Dr. A. Handlirsch made of the host of Hypoderma 
lineata Villers. He explains how the insect was traced to cattle, 
contrasts it with H. bovis, and gives some interesting information about 
the habits of these pests. It seems that the larva of H. bovis found in 
the skin of cattle is not strictly the first stage, but that there is a 
preliminary larval form in ovo before deposition is effected. 
Terminal Segment of Male Hemiptera.|| — Dr. D. Sharp describes 
this in twenty-nine species. It forms a chamber widely open exter- 
nally and contains the following structures : — (1) the part of the male 
organs through which pass the membranous structures connected with 
the ejaculatory duct ; (2) the termination of the alimentary canal which 
is free and very mobile, and forms a sort of tail ; (3) some accessory 
pieces of appendages, a lateral on each side and an inferior single piece. 
The differences in species systematically allied are extraordinarily great, 
but no variation was observed within the same species. “ The aesthetic 
aspect of the arrangement in many of the higher species is very remark- 
able,” but Dr. Sharp does not attach any special biological importance 
to it. The structures are not in any way modified for clasping ; they 
protect sensitive parts from pressure, exclude parasites, direct the move- 
* Zeitschr. f. Wiss Zool., li. (1890) pp. 55-160 (5 pis.). 
t Verh. K. K. Zool.-Bot. Ges., xl. (1890) pp. 301-6. 
J T. c., pp. 307-10 (1 pi. shared by the two papers). 
§ Verh. K. K. Zool.-Bot. Ges., xl. (1890) pp. 509-16 (3 cuts). 
|| Trans. Entomol. Soc. Lond. (1890) pp. 399-427 (3 pis.). 
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