COLEOPTEROUS INSECTS. 137 



DYTISCUS DIMIDIATUS. 

 PLATE IV F;s. r .. 



Bergstraesser Nomcnclatitr, pi. 7, fig- ! Curtis' Brit. Ent. 

 iii. pi. 09. 



The colour is brownish black tinged with oiiva 

 green. The antennae and upper lip are yellow, and 

 there is a triangular or crescent-shaped spot of rust 

 red on the forehead between the eyes. The thorax 

 is widely margined on each side with yellow, and a 

 broad stripe of the same colour runs along the w r hole 

 of the external margin of the elytra : the surface of 

 the latter is very smooth in the males, and each is 

 marked with three rows of punctures. The under 

 side of the body, and the legs, are yellowish, with 

 the sutures of the breast black. The lobes of the 

 sternum, which afford very distinctive characters in 

 this group, are obtuse in the present species. 



It has occurred at Cambridge, and in some other 

 parts of England. 



There is another group of aquatic beetles, the 

 species of which, although much inferior in size to 

 those just described, are still more fitted to attract 

 attention by their numbers, brilliant appearance, and 

 interesting manners. These insects constitute the 

 genus 



