2 3 



composing its walls are easily seen. Very fine salivary ducts pass 



forward from them and unite into a single tube beneath the labium, 



which presumably opens on the Moor of the mouth (Fig. ^c). The 



cesophagus leads into the cardiac chamber occupying segment 4. It 



originates at the posterior broad end of the cesophagus, and projecting Cardiac chamber 



forwards surrounds it like a cuff ; it is composed of a single layer of 



very large cells which bulge externally, but no true caecal processes, 



such as are found in C. dorsalis, exist in the cardiac chamber of this 



larva. The anterior edge of the cuff is supported by a pair of lateral 



muscles. The space between the inner surface of the the cuff and the 



oesophagus seems to be in free communication with the body-cavity. 



Peristaltic contractions starting from the anterior end can be seen 



from time to time to pass like a wave along the cesophagus and within 



the cardiac chamber to its base ; and this movement besides forcing 



the food down the cesophagus, will cause blood to circulate within 



the cuff and so nourish its cells. 



The cesophageal valve is a transparent funnel-shaped organ project- 

 ing from the base of the cesophagus some way into the stomach. It 

 has the effect of entirely preventing any food passing backwards from 

 the stomach into the mouth, while food still in the oesophagus is 

 frequently regurgitated into the mouth by larvae under the compressorium. 

 At the base of the pericardial chamber is a distinct constriction, and 

 immediately behind it the alimentary canal enlarges to form the stomach, 

 a wide tube lying in the central segments of the body. Within the 

 stomach and protecting it from direct contact with the food is the 

 peritrophic membrane, a clear chitinous tube attached to the stomach 

 at its anterior end only. Both the cardiac chamber and stomach are 

 coloured brownish yellow. At the junction of the stomach and the 

 small intestine are four short malpighian tubules. The small intestine 

 is a short slightly waved transparent tube and abruptly enlarges to 

 form the large intestine or colon, a large transparent thin-walled tube 

 opening to the exterior by the anus. 



From this short description it will be seen that the chief differences 

 between this larva and that of C. dorsalis are the simple form of 



(Esophageal valve. 



