148 ANATOMY. 



duct extends to the orifice. In Carabus auratus this body is a bunch 

 of small round vesicles ; in Car. cancellatus it is divided into two equal 

 halves, the two short ducts of which speedily unite into one. The 

 urinary bladder, which is wanting in Harpalus, is present in Carabus, 

 has the shape of a fig, and stands almost at right angles with the eva- 

 cuating duct. It is much the same in Cymindis Jtumeralis; in Aptinus 

 three equal ducts open into the bladder, each of which originates from 

 five granulated glands with five branches. In Brachinus the glands 

 are convolutions of shorter or longer, and sometimes furcate filaments. 

 In Chl(E?iius and Sphodrus there are many solitary granules, each of 

 which has a small duct, they all unite into one stem, which then opens 

 into the bladder. 



In the water beetles (PI. XXI. f. 11.) the portion lying above, and 

 over the urinary bladder, is but a simple, twisted, but tolerably long, 

 although delicate vessel ; the bladder, on the contrary, is round, but 

 not petiolated. It is the same in Bombylius. 



With respect to the structure of these organs, two membranes are 

 distinctly discerned in the evacuating duct, the interior of which is 

 much less than the exterior; this is constricted by parallel transverse 

 rings. The glands also have occasionally (Chlcenius velutlnus] similar 

 transverse rings, particularly when they are somewhat larger. 



114. 



CHANGES IN THE INTESTINAL CANAL OCCASIONED BY THE 



METAMORPHOSES. 



In the preceding description of the nutrimental canal in insects, 

 we have restricted ourselves chiefly to their form and structure in the 

 perfect creature. As, nevertheless, the differences which are produced 

 in the nutrimental canal by their metamorphoses are by no means unim- 

 portant, for the intestinal canal in larvae assumes very generally a very 

 different form, and its changes are subject to peculiar laws, partially 

 influenced by the order to which it belongs, we must not omit taking 

 notice of them as far as is possible in a general sketch, and must there- 

 fore make room here for a description of these transformations. 



Insects with an imperfect metamorphosis, viz. the Hemiptera, 

 Orthoplera, and Dictyotoptera, have in all their stages a very uniform 

 nutrimental canal. We find in them the same divisions in the same 

 proportions, and even the appendages, such as the salivary and biliary 

 vessels, agree with those of the perfect insect. The whole change, 



