THE society's NOTE-BOOKS. 93 



also, but in the slide before us the other feet are of the ordinary 

 form. In this genus the antennae are very variable. C, PL IV., 

 shows the antenna of Dolichopus longicornis. The antennae are pecu- 

 liar in structure ; but I think with the aid of the diagrams Z> and E 

 they may be understood. The second joint, Z>, has a thumb- 

 like process projecting from one side ; this process is received 

 into the interior of the helmet-like third joint, E^ and is articulated 

 to the bottom of it, in the same way as a clapper is articulated (so 

 to speak) to the bottom of a bell. F. J. Allen. 



Wings of Insects are always spoilt by caustic potash. To save 

 them entire, they should be cut off from the insect before it is 

 treated with potash, and placed in position on the slide at the 

 time of mounting. F. J. A. 



Haltere of Fly. —These organs, with some few exceptions, are 

 even more delicate than wings and are totally ruined by potash. 

 They are very beautiful objects, but their chief interest lies in 

 their being the probable seat of the sense of hearing. In his " Ana- 

 tomy of the Blow-Fly " Mr. Lowne goes deeply into the subject. 

 His conclusions are that the antennae are not organs of hearing, 

 but of smelling ; and that if insects hear at all they hear with 

 their wings. 



In the wings of most insects, on one of the larger nervures 

 near the base, may be seen a group of little spherical bodies 

 embedded in the substance of the wing. The theory connected 

 with these is that they are otoconia or ear-stones, floating in fluid, 

 and connected with auditory nerves, and that the sonorous vibra- 

 tions of the air are communicated to them by the membrane of 

 the wing, which acts as a tympanic membrane. It is believed that 

 in the Diptera one pair of wings is modified into halteres for the 

 special purpose of hearing, for although otoconia exist in the wings 

 proper, they are much more developed in the halteres ; moreover, 

 the haltere seems to be eminently adapted for receiving impres- 

 sions of sound. 



The haltere consists of a delicate membrane enclosing some 

 kind of fluid. It is strengthened by two nervures — one at the 

 anterior, the other at the posterior border, which are relics of the 

 nervures in the wings of insects. In the interior are a number of 

 oval, cell-like bodies with nuclei, whose functions I do not at all 

 know. 



At the base of the haltere are situated two groups of otoconia : 

 one on the posterior nervure, the other on the soft portion of the 

 haltere contiguous to the body. The latter group are irregularly 

 arranged, and do not appear in my drawings on the plate ; but the 

 former are arranged in rows across the nervures, and are shown at 

 Fig. F, and much more magnified in Fig. 6^, PI. IV. 



