MAECH. 65 



different states into which they pass, and explained the 

 great subdivisions of the order; the student will now be 

 better prepared to understand those species which are pre- 

 sented to his notice. The order Coleoptera, the first men- 

 tioned, was described, with its principal family distinctions, 

 in February. 



COLEOPTERA. HTDROPHILID^E. 



HYDEOU8. 



Generic Distinctions. Antennae short, and clubbed at the end ; 

 palpi long and slender ; mandibles largely toothed ; elytra nar- 

 rowing gradually behind ; tarsi five-jointed. 



HYDROUS PICEUS. (Plate I.) Ground-colour black, in- 

 clining to olive ; margins of the elytra faintly tinged with 

 purple and green ; antennae and mouth reddish ; wing-cases 

 marked with eight dotted lines ; a few yellow spots on the 

 body, and hairs of the same colour on the breast ; the legs 

 very dark, and fringed with reddish-brown. This is the 

 largest of our water Beetles, and is common in the south, 

 though becoming rare in the northern counties. The larva 

 is very destructive to small shell-fish ; it swims with great 

 facility, and can seize its prey without changing its position, 



