526 



Lieut. F. Tulloch. 



[Feb. 2, 



The slightly bulbous ends of the glands lie under the upper border of the 

 sucking stomach, and are found by following up the outer limb of the 

 exposed angle of gland. Except for this angular bend the glands are straight 

 in their whole course, and even when pulled out they are not long enough 

 to reach the hinder end of the fly. 



The salivary glands run up through the waist of the fly on either side of 

 the duct of the sucking stomach and ventral to the intestine, and continue 

 with the same thickness to the front of the thorax. At this point, in the 

 neck of the fly, the glandular portion ceases abruptly, to be continued as a 

 very fine narrow duct (fig. 1, D.S.G.). At first this duct is made up of small 

 flattened cells, but it almost immediately acquires the structure of a small 

 trachea, becoming chitinised and having similar annular thickenings. At 

 the base of the brain the two ducts join and continue as a single duct on the 

 ventral surface of the chitinous pharynx, inside the transparent membrane 

 which wraps it round. The dilatation in the common duct which Hansen has. 

 described and which he regards as a storage chamber for the secretion, occurs- 

 about half-way in the length of the common duct. The point of entrance of 

 the duct into the proboscis has been described by Hansen. 



Nervous System. 



This consists of the brain and the thoracic ganglion, with the nerves- 

 arising from them. 



The nervous system was not dissected in great detail, but the following 

 nerves were traced as described. The thick nerve to the ocelli arises from 

 the upper part of the back of the brain. The stout nerves to the antenna? 

 arise from the front of each cerebral ganglion. On either side of the front of 

 the brain below the nerves to the antennas arises the slender pharyngeal 

 nerve trunk, which shortly divides into three. The outermost of these three- 

 branches divides into two, one filament supplying the depressor muscle of the 

 pharynx which arises from the postero-superior process, and^the other running 

 down inside the pharynx in close relation to its chitinous wall. The middle 

 division of the pharyngeal nerve joins its fellow of the opposite side on the 

 wall of the oesophagus as the latter enters the pharynx, the common trunk 

 thus formed splitting into four branches to the intrinsic muscles of the 

 pharynx. The innermost branch of each pharyngeal nerve joins a slender 

 nerve arising in the middle line. The nerve thus- formed supplies the 

 pharyngeal muscles, but was not traced in detail. 



The brain is connected with the thoracic ganglion by the connectives, 

 between which passes the oesophagus and which join after this to form a long 



