82 INSECTA MADERENSIA. 



Sectio II. HYDRADEPHAGA. 

 ram. 2. DYTISCID^. 



Genus 25. COLYMBETES. 



ClairviUe, Ent. Helv. ii. 198 (1806). 



Cm'pus vel mediocre, vel (ut in specie nostra) magnum, plus minusve oblongum : alis amplis. An- 

 tenna filiformes. Labrum brevissimum, antice Icviter emarginatum. Mandibula; breves, apice 

 lato-emarginat?e, intus basi bidentatse. Maxilla bilobse: lobo externa palpiformi biarticulato : 

 inferno acuto incurve, ad apicem uncinato, intus valde ciliato. Palpi maxillares articulo ultimo 

 elongato-truncato : labiales articulo secundo elongate, ultimo paulo brcviore subarcuato. Mentum 

 transversum, antice profunde emarginatum et dente medio brevi trancato instructum. Liyula 

 quadrata, antice ciliata. Pedes natatorii : tarsis anterioribiis in maribus articulis tribus dilatatis, 

 subtus acctabulis obsitis : unguiculis anterioribus magnis valde curvatis sequalibus, posticis sub- 

 rectis inaequalibus, superiore fixo. 



The genus Cohjmhetes, embracing Uybitts and Agohns, Avhich are now regarded 

 as distinct, was established by Clau-ville in 1806 ; but it was not until 1817 that 

 it was restricted (as above defined), by Dr. Leach, to the larger members of the 

 group. As thus limited, it has, apparently, but a single representative in the 

 Madeii'a Islands ; namely — 



64. Colymbetes Lanio. 

 C. oblongus nigro-piccus, capitis parte antica maculisque duabus in fronte sitis et prothoracis lateribus 



rufo-testaceis, elytris testaceis densissime nigro-irroratis, singulo longitudinaliter profunde 



triseriato-punctato, antennis pedibusque rufo-ferrugineis. 

 Long. Corp. lin. 10. 



Dytiscus Lanio, Fab. Ent. Syst. i. 190 (1792). 



•, Oliv. Ent. iii. 40. 19. pi. 2. fig. 9 (1795). 



Cohjmhetes Lanio, Aube, Hydroeanth. 221 (1838). 



Habitat in aquis Maderse, prsesertim fluentibus, a 1000' usque ad 4000' s. m. ascendens : in rivulis 

 supra Funchal, necnon in Madera boreali in ascensu a Sao Vincente ad campum ilium Paul da 

 Serra dictum, a-state et autumno abundat. 



C. large, oblong, and somewhat convex; both sexes shining; piceous-black. Head and prothorax 

 (especially in the male sex) somewhat rcticulose : the former with its anterior portion (com- 

 mencing from the insertion of the antenna?), and two large transverse patches on the forehead, rufo- 

 testacoous, and with a sinuated impression on either side, between the eyes : the latter transverse, 

 impressed behind and before, and with the edges broadly rufo-testaceous. Elytra testaceous, and 

 exceedingly densely besprinkled with minute, black, and more or less confluent spots, wiiich 

 almost obscure the entire surface ; with three longitudinal rows of large and deeply impressed 

 points on each, the outer one of which is the least apparent. Legs and antenna rufo-ferruginous. 



