THE ORGANS OF DIGESTION. 147 



extend beyond the thorax. It is thence that we detect the salivary 

 vessels, with the exception of the very long ones of caterpillars, only in 

 the thorax. They here lie around the pharynx, crop, or stomach, gene- 

 rally low down in the breast between the coxae of the legs, whilst their 

 meandering evacuating duct, rising from beneath the nutrimental canal, 

 ascends to the cavity of the mouth, and here, after having united with 

 its companion, opens beneath the tongue. Locusta displays this 

 aperture very distinctly. In the bees, in which the salivary organ 

 consists of four granulated valves, the anterior one lies in the head, 

 directly beneath the forehead, before the eyes, and was originally de- 

 scribed by Ramdohr as the organ of smell, but subsequently recognised 

 as the salivary gland. The evacuating duct empties itself into the tube 

 of the proboscideal tongue, and is a spiral vessel resembling the trachea, 

 as Treviranus has described and figured it * ; in Locusta I found it 

 simple, thin, and transparent, but accompanied by a delicate trachea, 

 which followed it throughout all its ramifications and divisions. 



113. 



THE URINARY VESSELS. 



As the last distinct organ, but which is doubtlessly in strict con- 

 nection with the digestive apparatus, we must take some notice of the 

 variously formed urinary vessels, which empty themselves above the 

 anus. These, like the salivary vessels, are sometimes mere vascular 

 canals, at others glandular bodies which in the latter case unite into 

 one duct, to which not rarely there is attached a vesicular distension 

 the URINARY BLADDER. The duct of the latter is always separated, 

 and never unites to those of the opposite side, and empties itself 

 laterally contiguous to and above the anus, but strictly separated from 

 it by the anal valve. 



These vessels are found in all the Carabodea and the Hydrocantha- 

 rides, in many Heleromera (Blaps), and again in Bombylius and 

 Leptis, among the Diptera. Ramdohr, who first observed them, drew 

 them to the intestine, and called them anal vessels ; but Leon Dufour 

 subsequently described many of their forms in detail t. 



In their most simple form (in Harpalus) the urinary vessels appear 

 as reniform bodies contiguous to the colon, whence a short evacuating 



* Vermischte Schrif., vol. ii. p. 123. PI. XV. f. 1. 

 f Annales des Sciences Natur., t. 8. p. 6. PI. XIX. and XX. 



L 2 



