THE society's NOTE- BOOKS. 97 



ance to the insect, for the nerve supplying it is, with the exception 

 of the optic nerve^ the largest in the insect's body. On entering 

 the haltere it splits up into a multitude of filaments, one passing 

 to each vesicle, while the main branch proceeds along the shaft of 

 the haltere and ends in a loop in the globe. T. C. Watson. 



Halteres.— I find it stated that a Crane-fly continued to buzz 

 after being deprived of its halteres, so that they cannot have much 

 to do with that performance. The same authority states that a 

 Crane-fly deprived of one or both its halteres or winglets could not 

 fly at all, and he concludes that they must be used as air-holders. 

 Derham, on the other hand, states that Diptera, when deprived of 

 one of their halteres, flew one-sided, and he thinks they must be 

 to steady the flight. Probably they are compound organs and 

 used for both purposes — viz., for smell and as poisers. 



E. S. Angove. 



Halteres. — A quotation from Hurley's Manual of the hiverte- 

 brata will probably show that the function of the halteres is not of 

 such importance as the above writers appear to suppose. On 

 p. 439 it is stated : — " In many winged insects both pairs of wings 

 are developed, and take equal shares in flight. In the Diptera the 

 posterior wings are represented only by short processes of the 

 halteres. In the Strepsiptera, on the other hand, it is the anterior 

 pair of wings which abort. In all orders of winged insects, indi- 

 vidual cases of complete abortion of the wings occur, either in the 

 female alone or in both sexes. R. L. Hudson. 



Halteres.— Perhaps the most convincing proof that the halteres 

 of flies are modified wings is to be found in the fact that in the 

 pupa of many of these insects these organs are to be seen nascent 

 in what must be called true wing-cases, precisely similar to those 

 of the fore-wings in every respect except that of size. Thus, in 

 the Crane-fly, PI. IV., Fig. H shows the fore- wing case of the 

 pupa with the nascent wing inside. Fig. / is the hind-wing case, 

 with the haltere inside. It is impossible to doubt with such evi- 

 dence that the organs are homologous. The same thing may be 

 distinctly recognised in the pupa of the gnat, and even in the 

 larva when arrived at maturity. A. Hammond. 



Mica is a mineral occurring in metamorphic rocks ; it consists 

 of bright, shining plates, which can be split up into very thin 

 laminae. With polarised light it appears of a variety of lines, the 

 colour depending on the degree of thinness of the lamina. 



H. F. Parsons. 



Granite and Syenite are both rocks of igneous origin, formed, 

 under great heat and pressure, from masses of erupted matter 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. III. h 



