78 THE COCKROACH [CH. Ill 



placed two stiff spines; those of the middle and of the 

 posterior pair of legs are in no way peculiar and probably 

 merely play a part in the ordinary cleaning of the surface 

 of the body and legs themselves, but on the anterior tibiae 

 one of these spines, A C (Fig. 16), is much flattened and its 

 inner margin drawn out into a closely set series of teeth 

 (C T, Fig. 16), thus constituting a very beautiful comb: this 

 structure hangs over a deeply cut semicircular notch (G), 

 whose concavity is furnished with similar teeth, placed at 

 the base (i.e. upper end) of the first joint of the tarsus, 

 and almost in the angle between the tibia and tarsus. 

 If an ant or bee or any other Aculeate Hymenopteron 

 be watched when cleaning itself it will be seen that the 

 foreleg is from time to time hooked over the antenna and 

 passed along it. At such times the antenna is placed in 

 the semicircular notch of the tarsus and at the same time 

 the tibial comb-spine is placed against the antenna on 

 the opposite side. The antenna is thus combed and 

 cleaned on every side of its cylindrical surface simul- 

 taneously. It is interesting to find these insects, which 

 are undoubtedly the highest of the Class in intellectual 

 power, and which are almost unique in laying up stores of 

 food for their developing young (and, in some of the best 

 known, tending them with infinite care and foresight), 

 should thus be provided not only with a poisonous sting 

 for offence and defence but also with an elaborate con- 

 trivance for keeping in an efficient condition the all- 

 important sensory organs the antennae. 



There can be no doubt that the pollen brushes which 

 are so characteristic of the legs of many bees are but 



