228 TOPOGRAPHICAL ANATOMY OF THE 



will be treated of in a special chapter, in which the functions 

 and morphology of the several parts will be fully considered. 



The salivary lingual glands are long convoluted tubes, which, 

 as already stated, lie one on each side of the chyle-stomach in 

 the thorax. They are prolonged into the abdomen, lying at 

 first on either side of the proximal intestine, and then beneath 

 intestinal coil ; they terminate just in front of the rectum. 



The large folliculate salivary glands, accessory glands, so 

 frequently present in insects, are entirely wanting; but a 

 pair of small folliculate glands are found in the oral disc of the 

 proboscis, the ducts of which open on its oral surface, and 

 there is said to be a pair of minute glands at the proximal 

 extremity of the fulcrum (Kraepelin) ; I have, however, been 

 unable to establish the glandular structure of these, and am 

 inclined to believe they are merely minute fat bodies. 



The Nervous System in the Muscidae is greatly concentrated : 

 not only are the supra- and infra-oesophageal nerve-centres 

 united into a single complex mass, which I term the brain, but 

 all the remaining ventral ganglia are united in one centre — 

 the thoracic nerve-centre. There is also a proventricular 

 ganglion, corresponding with the proventricular ganglion of the 

 larva, which is united with the crura of the supra-oesophageal 

 ganglia by a median, stomogastric, nerve. The visceral nerves 

 arise from the proventricular ganglion. There is no frontal 

 ganglion lying, as is usual, in front of the brain, but it is pro- 

 bable that the nerve-cells on the inner surface of the crura of the 

 supra-oesophageal nerve-centres, from which the stomogastric 

 nerve arises, represent it. 



The structure of the nervous system is exceedingly complex, 

 and will be fully treated of in a separate chapter ; and the origin 

 and distribution of the somatic and stomogastric or visceral 

 system of nerves will also be more conveniently considered 

 hereafter. I will only add in this place that the brain is 

 apparently concerned in the reception of impressions derived 

 from the various sensory organs of the head, in the movements 

 of the proboscis, and in the initiation of such movements as may 

 be regarded as of an automatic, rather than a reflex, character. 



