1 9 1 o] A natomy of Cecidomyia resinicoloides 5 1 



segment 8, where it turns dorsally, closely following the Mal- 

 pighian tubes to which short branches are sent. 



Circulatory System. This system owing to its transparency 

 and delicacy was quite difficult to follow, and so a detailed 

 description of it cannot be presented. The dorsal vessel is a 

 thin- walled, transparent tube which arises in front of and below 

 the brain, and proceeds obliquely upwards until it meets the 

 body wall in the posterior part of segment 4 w^here it is secured 

 by the suspensorium. Thence it runs along the dorsum extending 

 at least to the posterior transverse tracheal tube. It is divided 

 into chambers and the valvular orifices (ostia) on either side 

 open and close inwardly. The dorsal vessel pulsates especially 

 in its anterior portion where there are several orifices. On each 

 side of the heart in the middle of segment 4 is a strip of loose 

 pericardial cells which proceed posteriorly, closely following the 

 vessel. 



Alimentary Canal. PI. VII, Fig. i. The alimentary canal 

 consists of the long slender oesophagus D, the larger scarcely 

 differentiated fore- and mid-stomachs (proventriculus and ven- 

 triculus) G, the slender and much curved ileum or small intestine 

 I, the colon K, and the rectum L. A pair of long, recurved 

 saHvary glands C. F. open into the mouth, and two Malpighian 

 tubules H. likewise recurved, are fastened to the fore part of the 

 ileum. The whole system is supported chiefly by the tracheae. 



Lying above the oesophagus and salivary glands and extending 

 well beyond the rods of the head skeleton is a large blind sac, S, 

 Figs. I and 2, PI. VI, which probably opens into the mouth. It 

 contains in its middle a curious, dark purplish-brown object. A, 

 Figs. I and 2, PI. VI, which is lobed anteriorly, and posteriorly 

 where it becomes semi-translucent and breaks up into small 

 granules. This object is evidently the ''point oculiforme" of 

 Giard (8), who noted it also in a Cecidomyia, but what its function 

 is he does not state. The large bUnd sac is apparently not 

 muscular, though it is possible that it may serve as a food reser- 

 voir. The ''point oculiforme'' suggests a strainer of some sort, 

 especially if the sac were muscular. The oesophagus extends to 

 the end of segment 3 as a very slender and delicate tube, and is 

 chitinized within the rods of the head skeleton, C, Fig. 2, PI VII 

 and Fig. 6, PI. VII. 



The large, straight, muscular stomach extends from the 4th 

 to the 8th segment inclusive,' and its cellular coat is made up of 



