82 . NORTHERN ZOOLOGY. 



II. BRACHELYTRA. Cuv. 



Having described the insects included in my plan belonging to the first great- 

 Coleopterous group, or section, both terrestrial, intermediate, and aquatic, I must 

 now turn my attention to the next, but which ought to be regarded as such, is a 

 question not yet fully decided ; since different Entomologists, and those of the first 

 eminence, having quitted the Adephaga, or predaceous beetles, distinguished by 

 the upper-lobe of their maxillae being palpiforzn, have pursued different routes. 

 M. Latreille places next to the aquatic Adephaga the Brachelytra of Cuvier, con- 

 sisting of the great Linnean genus StaphyUnus ; while Mr. W. S. Mac Leay takes 

 next the remainder of the aquatic beetles, as forming one great group, which he 

 denominates Philhydrida. 1 



This gentleman seems to wonder that so acute an Entomologist as M. Latreille 

 should not perceive an affinity which almost all other investigators of insects have 

 acknowledged: 2 the last mentioned author, however, in his most recent work, per- 

 haps with a view to this objection, has assigned his reasons for this opinion, and 

 they seem not devoid of weight. " The anatomy," he observes, " of these insects, 

 differs essentially. The alimentary canal of the Hydroph'di, has considerable an- 

 alogy by its length, surpassing four or five times that of the body, and by its texture, 

 with that of the Lamellicorns (Scarabaeus L.) and approaches that of the Adephaga 

 only with regard to its biliary vessels. They have neither the natatory vesicle, nor 

 the excrementitial apparatus which characterizes the Dytiscidas. In the ^females 

 that apparatus is replaced by organs secreting the matter that forms her egg-cocoon. 

 Finally, the male genital organs have the closest affinity with those of the preced- 

 ing family :" 3 — viz. the Clavicomes including the Silphidce, &c. M. L. Dufour also 

 observes, that this structure of the male genital organs, justifies M. Latreille in 

 placing his Palpicomes (Hydropkilus, &c.) where he does. 4 



If we further compare the oral organs of Hydrophilus with those of Dytiscus, 

 we shall find a striking difference. The mandibles are not precisely like those of 

 any other genus, but in one respect they resemble those of many Lamellicorns ; at 

 the base, on the inner side, they are furnished with a large molary space or plate, 5 

 but not striated. They are evidently fitted for strong work; at the apex is a stout 



1 Annulos. Javan. 6. 2 Ibid. 32. 3 Latr. Crust. Arachn. et Ins. i, 519. 



1 Ibid, note 1. 5 Linn. Trans, xiv, 105. Introd. to Ent. iii, 435. 



