a carnivorous Tipulid larva. 245 
masses of the filamentous substance. Moreover, the 
salivary fluid is not known to be used for other than 
digestive purposes. While admitting that the point is 
not proved, I am inclined to believe that the filaments 
are secreted by the salivary glands, and that during the 
life of the larva they are semi-fluid. 
At the junction of the esophagus and the stomach 
the longitudinal fibres emerge from beneath the annular 
fibres of the @sophagus in the manner described by 
Balbiani.* The two epithelia come abruptly into con- 
tact without any transition (fig. 18). 
Beyond the stomach the straight intestine extends 
to the anus; its wall is lined with longitudinally 
folded cuticle, and, except when food is passing, the 
cavity is obliterated. The longitudinal muscles are 
numerous in the intestine, and external to the annular 
muscles, as in the stomach. ‘he intestinal epithelium 
contains comparatively few nuclei of unusually large 
size. Close to the anus the iutestine dilates a little, 
and here the annular muscles become crowded. This 
section corresponds to the rectum of the fly, but is 
small, almost rudimentary, in the larva. 
There isa pair of salivary glands of moderate size, 
filled with a clear fluid, coagulable by alcohol. The 
epithelium of these glands, as in the larve of Musca, 
Chironomus, and Simulium, is remarkable for its large 
nuclei. ‘The paired salivary ducts unite behind the 
head to form a common duct, which opens into the 
mouth. I believe that the saliva has in this larva a 
purely digestive function ; at least, I do not know that 
threads are ever emitted from the mouth. There are 
four long Malpighian tubules, given off, as usual, from 
the beginning of the intestine. 
The straightness of the alimentary canal, and the 
absence of the large diverticulum found in the vegetable- 
feeding larve of Tipula and Ctenophora, are obvious 
adaptations to a carnivorous diet. 
The Circulatory Organs of the Larva. 
The dorsal vessel, enclosed in a wide pericardium, 
occupies the usual position, extending from the last 
segment to the brain. 
* Loe. cut., p. 17, 
