390 DR. J. B. HICKS ON THE ORGANS 



are few and long ; whilst the apex, which has three spinous processes which are supplied 

 with a nerve, doubtless possesses the sensation of touch (sec M. figs. 1, 2, 3) . 



In Meloe the antennse consist of eleven joints, of which the 1st, 2nd, 3rd, and 9th are 

 not fiu'nished with the organs, as aU the rest are, especially the 6th, 7th, 10th and 11th : 

 those in the last, or 11th, are the largest. They have the same form as those of the Necro- 

 phora Vespillo, hut rather smaller. 



In Clytus arcuatus the sacs are found interspersed between the hau's, of the diameter 

 of sooo inch, xa. considerable number on the last five joints, and of the same form as in 

 Necrophora Vespillo. 



I shall next describe the antennae of the Jlymenoptera. 



In the genus Vespa, whose antenna I have described in my former paper, I have since 

 had an opportunity of examining the antenna of the male, female, and neuter, both of 

 V. vulgaris and also V. Crabro. In aU these, as there described, the last ten joints are 

 covered on aU sides from base to apex by organs having the canoe-shaped closing-in mem- 

 brane. The number of these on each antenna of V. vtilgaris is procUgious ; on each seg- 

 ment there are rather more than 2000. The 3rd segment possesses rather fewer, and the 

 12th rather more, making altogether on the ten segments 20,000 for each antenna. There 

 are also on tliis antenna many dwarfed hairs, as on that of Dyticus marginalis. Tliere is 

 no particular difference between the different sexes and neuters ; and I may add that a 

 distinct sac is visible behind the oval opening, which is seen behind the canoe-shaped 

 closing-in membrane. 



In Apis mellifica, however, the antenna of the worker or neuter (described in my 

 former paper) possesses the organs only on one side ; whilst in the drone or male the 

 antenna is entirely covered with them, similar to those of the male Eucerus longicornis 

 (see former paper, PI. 30. fig. 7). I have, unfortunately, not succeeded in obtaining a 

 female or queen, to enable me to institute a comparison : still one would argue that if 

 these organs were olfactory, we ought to find them ia a peculiar degree developed in the 

 workei', and scanty in the male, who seldom leaves the hive, and then only for a short 

 distance ; but the contrary is the case. 



Odynerus murarius possesses organs very like those of the neuter Apis mellifica, situated 

 on one side ; and as the other side is free from any markings, the nerve and its distribu- 

 tion and the accompanying tracheae can be beautifully seen. The nerve, accompanied by 

 two tracheae, passes from base to apex, through the centre, giving off a branch from 

 either side, about the centre of each segment, which branch passes through the next joint, 

 to be distributed to the organs in the succeeding segment, and again giving off numerous 

 fibres to supply the organs with sensation. 



A remarkable antenna among the Hymenoptera is that of the Hed Ant, Myrmica rubra. 

 It consists of twelve segments : the first is very elongated, the rest being joined to it at a 

 right angle ; the segments after the second gradually increase in width to the last, which 

 is longer than any, except the first, and tapers gradually to a point, towards which the 

 antenna- wall gradually becomes thiimer, so that at the extreme apex it is very delicate, and 

 the bail's also abbreviated. The surface is furnished tolerably thick with hairs, as in most 

 antennae. It also possesses the sacs very weU marked, as may be seen at N. fig. 1 a, 3 a, 4. 



