THE BEETLES 



3097 



day, lying in wait for their victims at the mouth of the holes. The genus Zabrus, 

 which we have next to notice, forms, so far as its habits are concerned, one of 

 those exceptions that go to prove the rule. For, while it is true that almost all the 

 Carabidce are carnivorous and predaceous insects, some at least of the species of 

 Zabrus and a few others are largely, though probably not wholly, addicted to a 

 vegetable diet. The species (Zabrus gibbus] figured on p. 3092 lives in cornfields, 

 and has at different times committed great havoc among crops wheat, barley, rye, 

 etc. , in various parts of Germany and Italy. 



The Dytiscidce or carnivorous water beetles resemble the Carabidce in many of 

 their structural features, and differ chiefly in the modifications undergone to fit them 

 to an aquatic mode of life. Thus we find, as in the latter family, the mentum is 



Dytiscus marginal** 1. Male; 2. Female; 3. Eggs; 4. Pupa; 5. I,arva attacking a tadpole; 6. Hydrocharis eara- 

 boides; 7. Its larva; 8. Acilius sulcatus, Female. (All natural size.) 



usually broad and deeply emarginate in front, the outer lobe of the maxillae is two 

 jointed and palpiform, the antennae are moderately long and slender, and the tro- 

 chanters of the hind-legs are prominent. On the other hand, the antennae are al- 

 ways smooth; the head is broad and fits deeply into the prothorax, while the latter 

 is applied by a broad base against the elytra, so that the outline of the body is con- 

 tinuous, and the general shape more or less oval; the hind-legs, which with their 

 tibiae and tarsi flattened and furnished with rows of bristles, are adapted to serve as 

 oars in swimming, are somewhat longer than the other legs, and come off from the 

 body at a considerable distance behind them, while their coxae appear as broad flat 

 plates firmly joined to the metasternum, for parts of which they might at first sight 

 be very readily mistaken. The males may be distinguished from the females by the 

 shape of their fore-tarsi, in which the first three joints are strongly dilated, and 



