ORGANS OF SENSE. 



27 



to, yet in many points differing from, what we find in the Verte- 

 brates, yet we know nothing, as a matter of fact, about their other 

 senses, which may be entirely different from anything of which we 

 have any conception. We can only pick out certain structures 

 and say that they have apparently to do with smell, taste, or 

 hearing, but we may be quite mistaken. In fig. 17, some of these 

 organs are represented. We have first (A) the apex of the antennse 

 of a larva of Pentodon punctatus (Dynastim), with a sensory 

 plate (a) and sensory hairs (str), and also the apex of the palpus 

 of an adult Melolontha (B), with sensory hairs or setae ; we cannot, 

 however, say with certainty whether these have to do with smell,, 



Fig. 17. — Organs of sense in Coleoptera : — A. Pentodon punctatus, apex of 

 antenna of larva ; a, sensory plate ; str, sensory hairs. B. Melolontha, 

 apex of palpus. C. Autennal pit of Melolontha vulgaris. D. Antennal 

 teeth of Anophthalmias tellkampfii. (After Berlese and Hauser.) 



taste, or hearing. One of the antennal pits of Melolontha vulgaris, 

 seen in a vertical section, is represented at C. These pits, which 

 occur commonly in the Lamellicorkea, have been referred to above ; 

 they are very remarkable both for their structure and their number. 

 Packard says of them (Text-Book of Entomology, p. 275): — " On 

 the outer surface of the first and seventh (in the female the sixth) 

 antennal leaf, as also on the edges of the other leaves, only arise 

 scattered bristles ; on the inner surface of the first and seventh 

 leaves, as also on both surfaces of the second to the sixth leaves, 

 are close rows of rather shallow depressions of irregular form, 

 some circular, others regularly hexagonal. Their number is 

 enormous ; in the males 39,000, in the females 35,000, occur on 

 each antenna." We cannot, however, say what their real sensory 

 function is, although it is quite evident that it is very important ; 

 it may be auditory or it may be olfactory, or both. Curious 

 antennal teeth occur in Dytiscus and in the blind Carabid Anoph- 

 thalmus ; some of these, on the edge of the antennae, are shown 

 at D. These teeth are interpreted by Packard as organs of smell, 

 but they may be organs of hearing or even of taste, like the minute 



