NO. 8 ANATOMICAL LIFE OF THE MOSQUITO SNODGRASS 



33 



stomodaeum into the mesenteron. The cardia is followed by a long, 

 straight tube, the stomach, or ventriculus (Vent), that extends back 

 into the seventh abdominal segment. The anterior end of the ventricu- 

 lus bears a circle of eight large pouchlike diverticula, the gastric 

 caeca (GCa). The dark mass of food particles in the ventriculus is 

 contained in a thin tubular peritrophic membrane (PMb), shown by 

 Wigglesworth (1930) to be secreted by the cell walls of the cardia 

 surrounding the stomodaeal funnel. The proctodaeum, or intestine, 

 is differentiated into a short anterior part (AInt), and a longer 

 posterior part, or rectum (Red). The anterior intestine begins as an 

 expansion against the end of the ventriculus, and then narrows to a 

 tube that makes an S-shaped bend to the saclike anterior enlargement 



Car GCa 



Fig. 12. — Lengthwise section of a Culex larva, showing the alimentary canal. 



AInt, anterior intestine; An, anus; Car, cardia (anterior part of ventriculus) ; 

 GCa, gastric caeca ; Hstm, hypostomium ; Mai, Malpighian tubules ; Mth, mouth ; 

 Oe, oesophagus ; Phy, larval pharynx ; PMb, peritrophic membrane ; Red, 

 rectum; SlGld, salivary glands; Vent, ventriculus (stomach). 



of the rectum, which finally proceeds as a narrow tube to the anus 

 (An). 



For a detailed study of the general structure, histology, and move- 

 ments of the larval alimentary canal of Anopheles the reader is 

 referred to a forthcoming paper by Jones (in press). 



The Malpighian tubules. — The excretory Malpighian tubules of 

 the larva (fig. 12, Mai) are five in number. They arise from the an- 

 terior end of the proctodaeum, first going forward into the sixth 

 abdominal segment, and then turning posteriorly to end in the sub- 

 terminal segment around the rectal sac. 



The salivary glands. — The larva has a pair of small salivary glands 

 of various shapes lying ventrally in the thorax (fig. 12, SlGld). The 

 ducts unite in a common outlet duct that enters the head and opens on 

 the labiohypopharyngeal surface just below the mouth (fig. 15 A, 

 SIO). The glands usually consist each of two parts of different shape 



