CONSIDERATIONS. 129 



to the general rule. Clems apiariiis is generally met with 

 in flowers, hence we might conclude that it fed on honey or 

 pollen ; it however is only hunting there for small insects. 



In the Orthoptera it is difficult to determine the food of any 

 species from the form of the tropin ; the herbivorous and 

 carnivorous ones are alike furnished with a molar surface, and 

 the maxilla and labium afford no distinguishing character 

 between these. This also applies to the Neuroptera. In the 

 Hymenoptera the structure of the mouth has undergone much 

 change, but its variations, caused by the nature of the food, are 

 much the same as those of the mouth of Coleoptera. In the 

 Hemiptera the mouth is still more changed, so that the whole 

 of the species are suctorious. Those which feed on the fluids 

 of animals, differ only in the general structure of the mouth 

 from plant-sucking tribes, in having its parts more firm. The 

 mouth of Diptera resembles in some respects that of Hy- 

 menoptera, the parts having undergone less degradation in 

 structure than in the Hemiptera. It offers no general cha- 

 racter which distinguishes the blood-sucking species from the 

 other. The genus Pulex, forming a separate order placed 

 near the Diptera, to which it approaches by the form of its 

 rostrulum, as well as by its complete metamorphosis, seems to 

 place itself at their head immediately after the Hymenoptera, 

 its labium being furnished with palpi and covered by the 

 maxillce. 



The food of the Lepidoptera being invariable, there can be 

 no change of form in the parts of the mouth arising from this 

 cause. 



The intestinal canal has always its two orifices distinct one 

 from the other ; d the mouth in the Annelida, Arachnida, and 

 in Insects, is always placed at the anterior extremity of the 

 head ; in the Crustacea it is mostly situated in the under 

 surface of the trunk ; the anus, however, is constantly placed 

 at the posterior extremity. 



The intestinal canal varies much, as well as to its disposition 

 as in its form and length ; its variations are not rigorously 

 in relation with those of the parts upon which we rest our 

 classifications, hence we can only lay down very general 



d Many Zoophytes have but one orifice to the intestinal canal ; the excrements 

 pass through the mouth. In insects the anus is sometimes wanting, and some 

 perfect insects have no mouth. 



NO. II. VOL. II. S 



