134 



ANIMAL PHYSIOLOGY. 



[LESSON 38. 



615. It has been remarked that those animals that subsist on 

 * animal food, have a short and simple form of the n^trimenta! organs : 



such is the case with the Tiger beetles ; moreover, they are not sub- 

 ject to much convolution, but are found nearly straight. 



616. A figure of the alimentary canal of Cicindela campestris, 

 which is a beetle common in this country, and in Europe, is given 

 (Fig. 218). The oesophagus is shown at a; it soon dilates into a 



FIG. 219. 



FIG. 218. 



Alimentary canal Cicindela campestris. 



Crop of Dyticus marginalis. 



large crop (6), the surface of it being covered with minute follicles. 

 This is succeeded by a small, but strong muscular gizzard (proven- 

 triculus), c, the interior of which is lined with teeth. The gizzard 

 opens directly into the true stomach (ventriculus), also covered with 

 follicular appendages (d). 



At its lower portion the pyloric valve is placed, and in that 

 neighborhood the biliary ducts (e) pour in their secretion ; it is not 

 quite clear, however, whether the valve be situated below these bile 

 ducts or above them. 



The intestine (/), commences beneath the biliary vessels, and 

 terminates in a short, dilated colon (g). 



In the large aquatic beetle, Dyticus margindlis, found as abun- 

 dantly in the ponds of this country as of Europe, the crop is of large 

 size, and terminates in a gizzard provided with four large triangular 

 teeth (Fig. 219). The crop (a) is a capacious bag, its interior beset 

 with very minute teeth, and deeply furrowed ; the proventriculus, or 



