ANNULOSA JAVANICA. 31 



Fara. 4, DYTISCIDCE. 



The larvee of these insects have not the lateral branchial appendages of the Gyrinidce, and 

 are therefore much less scolopendriform. Indeed their sub-convex and rather conical body 

 with various other circumstances might, on a first view of them, make us place them out of 

 their natural situation ; but their obvious analogy to the larva? of Hemerobii, as well as to the 

 larva? of Geodephaga, will serve to make them known to the practical entomologist. 



There are few insects so voracious as the Dytiscidce, and their power of moving at will either 

 in the water, in the air, or on the earth, gives them ample means of satisfying then- 

 rapacity. 



I may in this place make the remark, that aquatic insects do not among themselves differ so 

 much in form as terrestrial insects. It is not merely that they are fewer in species, and therefore 

 may be expected to form fewer genera, but that the tropical genera of aquatic insects are much 

 the same with our own, or at least are not so different from each other as the tropical and Euro- 

 pean Geodephaga. Another remark to be made is, that aquatic insects are in general as large 

 or larger with us than they are within the tropics. I know of no Hydrophilidce larger than our 

 Hydrophilus piceus ; and the largest of the Dytiscidce, that has ever come under my notice, is 

 the D. latissimus of Sweden. The only exception to this remark among the Hydradephaga 

 occurs in the Gyrinidce, as for instance in the genus Dineutus above described. 



Genus COLYMBETES Clairv. 



60. Octodecim-maculata. C. niger capite maculis tribus, thorace marginali, elytris vitta marginali maculisque 



novem Jlavis. 



Long. corp. & 



Caput maculis tribus mediis Thoraxque macula marginali flavis. Elytra striis tribus punctorum obso- 



letissimorum, vitta marginali nee basin nee apicem attingente, maculis flavis tribus basalibus, 



quatuor mediis fasciam fere formantibus et duabus apicalibus. Corpus subtus nigrum abdominis late- 



ribus rufo-maculatis. Pedes quatuor antici flavi. 



61. Fabricii. C. collo nigro, thorace riifo, elytris cinereo-ritfoque striatis. 



Dytiscus varius. Fab. Syst. Eleuth. i. p. 267, 48. 



Long. corp. § 



Obs. Fabricius described an insect in the Ent. Syst. which he found in the Banksian cabinet, 

 and called it D. varius. Afterwards he confounded a Sumatra insect, which he found in Daldorff s 

 cabinet, with his D. varius, and altered the original specific character to suit his new insect, 

 which I here call D. Fabricii. 



62. Suturalis. C. elytris cinereo-nigroque variegatis : stiiis tribus punctorum impressis sutura nigra lineaque 



utrinque rubra. 



Long. corp. 1 



Caput obscure ferrugineum punctis duobus impresses medio utrinque nigrum, ore palpis antennisque 



testaceis. Thorax glaber lavis marginatus subcanaliculatus rufus macula media transversali nigra. 



Elytra punctis numerosissimis approximatis nigris cinereisque variegatis, striis punctorum obsoletis. 



margine exteriore rubro. Corpus subtus nigrum, pedibus quatuor anticis femoribusque posticis piceis. 



63. VlTTATUS- 



