INSECT VAllIETY. 



219 



callis elinguaria) they project into the abdominal air-bladders in 

 the form o£ two isolated pear-shaped bodies, partially divided 

 by a septum, and terminated by an iridescent mirror-like mem- 

 brane. It has been fancied the more slender butterfly-like 

 species of the Geometrina have auditory power, and certain 

 experiments are recorded in Nature that were made on the 

 acoustic susceptibilities of the large Magpie Moth. In the 

 Sphinx Moths indications of the external auditory cavity appear 

 commonly wanting, yet possibly the stridulating kinds have 

 powers of communication. It may be remarked the late Colonel 

 Goureau, in searching for the musical organ of the Death^s Head 

 Moth, mentions a white muscle, inserted into the borders of a 

 slight cavity covered with smooth transparent membrane, on 

 either side of the first abdominal segment, just beneath the 

 insertion of the fan. 



Among the flies and bees, which are commonly unprofitable 

 objects for such investigation, I fancied I once found something 

 corresponding to this structure in certain Crane Flies ; and Dr. 

 Seudder finds a thoracic nerve in Bumbles which he thinks may 

 serve for hearing, but there is in the latter instance no external 

 indication. 



ORGAN OF HEAUING IN THE COLEOPTERA. 



With regard to those longieorn beetles that stridulate and 

 reply when perched many yai-ds apart, in the fashion of the 

 grasshoppers, leaf-crickets, and Cicadse, we might surmise the 

 existence of auditory organs of some dimensions, although 

 further than certain peculiarities in the structure of the forelegs 

 I find nothing suggestive of such. The species of Dung Beetle 

 ( Geotrupes) stridulate in concert when boxed together. The male 

 does so when chasing the female ; and on approaching an indi- 

 vidual of this genus walking on the road, it is seen when the 

 observer arrives at a few paces^ distance suddenly to contract its legs 

 and remain motionless, so that these likewise might be with little 

 doubt attributed with hearing. Here too, certainly, structural 

 indications are present, though minute, of organs presumably 

 sound-perceptive. For in this genus we find anteriorly four 

 ganglia (Plate VII., Fig. 4). The first is oval, situated at the 

 posterior part of the head ; the second diamond-shaped, and 



