48 THE BUTTERFLIES OF KEW ENCiLAXD. 



Digestive system. As a whole, the digestive system is usually some- 

 what longer than the body, though its convolutions are entirely confined to 

 the intestine proper in the hinder part of the abdomen. Its most peculiar 

 feature in butterflies is the complicated a[)paratus by means of which the 

 food enters tlie stonuich, the exact method of operation as well as the 

 organic foundation of the same having been discovered and well elucidated 

 by Burgess (87 :3,5, 9, 23). As we shall describe this somewhat in detail 

 in the body of this work, it is only necessary to say liere that Ijy means of 

 a highly muscular pliaryngeal sac a \acuum is [)roduced within the body, by 

 which the fluids are sucked up the moutli-tube, and are prevented from 

 returning the same way by a simple valve at tlie anterior extremity of tlie 

 sac. The sac 0})ens directly into a long and slender oesophagus and the 

 parts that follow show little variation within the whole tribe of butterflies , 

 80 far as I have seen, probably due to the great general similarity of their 

 food, — honied vegetable secretions or decomposing vegetation. The oeso- 

 phagus is a jjcrfectly straight and uniform tube extending to the very base 

 of tlie alxlomen. Here, just before it enlarges to form the stomach, it has 

 an independent enlargement of its own, from the upper surface of which 

 the so-called food reservoir (61:46,47,50) takes its rise: this organ, char- 

 acteristic of Lepidoptera and therefore doubtless connected with its peculiar 

 means of obtaining nourishment (though its actual use is still unknown), 

 is a large, bladder-like, elongated vessel lyiug upon the stomach in the 

 anterior half of the abdomen, bluntly rounded behind, tapei'ing in front 

 to a rather slender neck, through which it enters the vestibule of the 

 stonuich. Cuticular processes (61 :o6,45), like moistened and therefore 

 tapering pencils of hairs, line the inner surface. The stomach is likewise a 

 straight, cylindrical or fusiform tube, three or four times the diameter of the 

 intestine but still slender, extending through about half of tlie abdomen, 

 when it contracts to nearly its initial size to form a short, oval, occa- 

 sionally cylindrical passage, a little larger than the succeeding intestine, into 

 whicli the malphigian vessels enter. Burgess describes no such chamber 

 separate from the stomach in Anosia, into the posterior part of which he 

 makes the malphigian vessels enter ; but in Mancipium, as figured by 

 Herold, this chylific ventricule is clearly distinct from the stomach and rather 

 forms a part of the intestine. The intestine is a slender cylindrical tube, 

 according to Dufour (who distinguishes the chylific ventricule), swollen at 

 its origin in A^anessidi and Papilionidi, but uniform in Anosia and jNIan- 

 cipium ; and terminating after its s-shaped curve in a pyriform or cylindri- 

 cal chamber, the colon, which is simple in Anosia, but in others, such as 

 jVIancipium, provided with an anterior coecal sac. The colon passes in- 

 sensibly into a slightly tapering rectum, with the anal opening at the 

 extremity of the body. 



^Vt the anterior end of the alimentary tract, just beneath the pharyngeal 



