14 ON THE ANATOMY OF THE FLY. 



The first class comprises five nerves,'-' those of the great 

 compound eyes and antennas, and the single nerve which 

 supplies the ocelli, or simple eyes. 



The two remaining pairs of nerves are distributed to the 

 proboscis. The larger supply the greater part of that organ, but 

 chiefly the palpi and lips, and the smaller, which give off 

 filaments to the two small ganglia already mentioned, are 

 almost entirely lost in the muscles of the pharynx. Both pairs 

 are probably motor-sensory, or compound nerves. 



The cephalic ganglion is in fact the centre of the special 

 senses in the fly. It is the analogue, that is the physiological 

 equivalent of the ganglia at the base of the cerebrum in ver- 

 tebrates ; and if, as I firmly believe, the antennoo are organs of 

 smell, it strictly represents the olfactory and optic lobes of 

 fishes. Next to bees and ants, that of the blow-fly is the largest 

 known in any insect proportionally to its size, being about 

 thirty times larger than the cephalic ganglia of the larger 

 beetles. But a more positive indication of a higher type of 

 organization than even the relative bulk of the sensory ganglia 

 is found in the fact that two very remarkable convoluted nerve 

 centres connected by a commissure, each about l-30th of an inch 

 in diameter, surmount the cephalic ganglion, and are connected 

 to it by a pair of distinct peduncles ; these are extremely like the 

 pedunculated convoluted nerve centres which occupy the same 

 position in bees and ants, first described by M. Felix Dujardin,f 

 and considered by him as analogous to the cerebral lobes of the 

 higher animals. That naturalist failed to distinguish these organs 



* There is no nerve corresponding to the recurrent nerve of Lyonet 

 falsely called sympathetic by some authors, but a true sympathetic or 

 organic nerve system exists in the fly. 



f F. Dujardin sur le Syste"me Nerveux des insectes., Ann. Sc. Nat. 

 Serie III. Tom. xiv. 195. and " Quelqucs Observations sur les Abeilles " 

 Ibid, xviii 231. 



