STRUCTURE, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY, 545 
PLATE 33. 
Fic. 29.—Alimentary system of mature larva. The course of the ventriculus 
and intestine as they lie in the larva is shown by the dotted lines. The 
origins only of the Malpighian tubes are shown. 
c.s.d. Common salivary duct. c.v. Caecum of ventriculus. zzé. Intestine. 
m.t. Malpighian tubule. @. Gsophagus. pA. Pharynx. pv. Proventriculus. 
r. Rectum. s.g/. Salivary gland. v. Ventriculus. 
Fie. 30.—Transverse section of a portion of the ventriculus of mature 
larva. (Camera lucida drawing.) 
e.v. Epithelial cell of ventriculus showing large active nucleus and striated 
peripheral region of cell. g.s. Probable gland cells. ¢.c. Group of imaginal 
cells. 
Fic. 31. Horizontal section of posterior or ‘‘ cardiac” region of the dorsal 
vessel. (From camera lucida drawings.) 
os. Ostium. v. Valvular flaps guarding the same. 
