COLEOPTEROUS INSECTS. 143 



of the anterior legs. The species figured is about 

 nine lines long and five broad. The colour is blu- 

 ish black, slightly glossed with purple, and having 

 faint coppery reflections ; the whole surface highly 

 polished and resplendent. During life the purple 

 and blue form pretty distinct bands on the elytra, 

 especially towards the sides. The under side of the 

 body is pitch brown, the natatory legs paler : the 

 fore-legs are very long, and of a brownish-black co- 

 lour. It was received from Java. 



Three principal or typical forms prevail among 

 beetles of strictly aquatic habits, to one or other of 

 which nearly all of them may be regarded as refer- 

 rible. Two of these have just been described as 

 characterising the families Dytiscidce and Gyrinidcs, 

 and we shall now proceed to point out the distin- 

 guishing marks of the third. Many of the species 

 of which it is composed formed a part of the great 

 LinnEean genus Dytiscus, but they differ so essenti- 

 ally from the insects to which that term is now ap- 

 plied, that Latreille, in his systematic arrangement, 

 has removed them to a great distance from their 

 former associates. Most other naturalists, however, 

 have to a certain extent preserved the connection, 

 owing to the affinity that arises from their inhabit- 

 ing the same element, and presenting some points 

 of resemblance in structure. The most striking 

 character is the great length of the maxillary palpi, 

 which are often considerably longer than the an- 

 tennae — a circumstance which has led the group to 



