16 C. HERBERT HURST. 



directed diverticulum of this crop is found arising from its ventral 

 wall. The crop appears at a later stage than that shown in Fig. 7. 



The cavity of the stomach becomes wider, while the part behind it 

 becomes narrower, with the exception of the rectal pouch. 



The salivary glands, which at the beginning of pupal life were 

 a pair of hollow unbranched club-shaped organs lying at the sides of 

 the alimentary canal in the anterior part of the thorax, become during 

 pupal life divided into about four branches, and the cavity almost 

 disappears, and acquires a pretty thick chitinous lining. The duds 

 run downwards to the neck, which they traverse at the sides of the 

 nerve cords. Just below the hinder border of the sub-cesophageal 

 ganglia they unite to form a median duct, which runs forwards to 

 open into a pit at the base of the hypopharynx. This pit becomes 

 deeper during pupal life, and acquires a very thick chitinous lining. 

 From it a deep groove, also very strongly chitinised, runs downwards 

 along the middle line of the anterior surface of the hypopharynx to 

 its extremity. This is true of both male and female ; but the hypo- 

 pharynx of the male is inseparable from the labium. 



The Circulatory System. 



The heart lies in the abdomen in a median space between the 

 extensor muscles and close beneath the dorsal wall of the body. It 

 arises at the anterior end of the eighth segment, and ends suddenly 

 at the anterior end of the first segment, giving off the aorta from the 

 ventral border of its anterior end. From its sides " alse cordis " run 

 outwards beneath the extensor muscles and between the main 

 tracheal trunks and the stomach, to be attached to the " peritoneal " 

 covering of the tracheal trunks, or to the outer layers of the wall of 

 the stomach. Each " ala " consists of a dorsal and a ventral lamina, 

 the two running together some distance from the heart. The space 

 between them has been called " pericardium " : it contains the 

 " pericardial cells," and communicates freely with the body cavity by 

 the spaces between the alse. The ventx^al lamina of each is con- 

 tinuous with the corresponding lamina of the other side of the 

 body, and all the ventral laminae together thus form an imperfect 

 " pericardial septum " (Graber). The dorsal laminae are attached to 

 the sides of the heart near the dorsal surface, their fibres taking a 



