"Appendix^^ of the Antenncp of Coleopterouft harvv. l/io 



tliat of tlie fourth or terininal sogment. It coiisij^tsof a short 

 chitinous or seinichitinous collar or stalk, supporting a cap 

 composed of a thin transparent cuticular membrane, which 

 appears to be of the same thickness throughout and to be 

 lined by very small cells. The cap is in the form of a short 

 cone with curved sides, and is strengthened at the l)ase where 

 it joins the collar by a narrow and thickened chitinous ring. 

 Lying within the laterally expanded distal portion of the 

 third segment, at a short distance from the base of the collar, 

 I was able to recognize what seemed to me to be a ganglionic 

 swelling of the antennary nerve, containing a number of 

 nerve-cells from which fibres or rods were seen to extend into 

 the collar. These fibres did not seem to pass beyond the 

 chitinous ring, and were oidy visible when focusing between 

 the upper and lower portions of the ring. In view of the 

 probable auditory nature of the organ I tried to detect the 

 presence of the characteristic auditory rods which are found 

 to be associated with the auditory apparatus in other insects. 

 My failure in this endeavour was perhaps due to the want of 

 a sufficiently high microscopic power. 1 am inclined, never- 

 theless, to suspect that within the collar, and just below the 

 ring, rods of this kind may be found. I was also unable to 

 satisfy myself as to the nature of the contents of the cap, 

 though it seemed quite evident that it contained no otoliths. 

 Whether the ring supports a transverse partition is another 

 point I could not satisfactorily determine, though the ap- 

 pearances were rather in favour of believing that it does. 

 These, however, are points that will have to be settled by 

 further investigation. The presence of a nerve-ganglion with 

 fibres passing out to the organ will also, I admit, need con- 

 firmation. In the few preparations I was able to make 

 nothing more was attempted than to clear the integument 

 slightly before finally mounting the antenna in balsam. [ 

 regret that, owing to lack of sufficient material, I could not 

 proceed to examine the structure of the organ more thoroughly 

 by means of staining and sectioning. Tliis I hope to be able 

 to do later on. 



Should the organ eventually be definitely proved to possess 

 a sensory function little doubt would, I think, arise as to its 

 auditory character. From its position and the way in which 

 it is guarded by some long stiff setai it would be more or less 

 prevented from coming in contact with external bodies ; so 

 that it would be almost impossible for it to function as a tactile 

 process ; while, on the other hand, its general structure seems 

 to preclude the idea of its being an olfactory organ. There 

 are, moreover, on the same distal surface of the third segment, 



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