286 On Aquatic Carnivorous Colcoptera or DytiscidcB. 



I. VS.— Genus DEROVATELLUS. 



Mesosternum not much exposed between the prothorax and metasternuni : 

 ventral sutures ordinary : size less than 4 m.m. 



Only one species is known ; it has occasionally been found in some numbers in 

 the New World. 



91. Vatellus lentus, Wehncke Stet. Zeit. ISiG, p. 357. — Oblongo-ovalis, subtiliter 

 sed evidenter pubescens, fortiter punctatus, subnitidus, rufescens, capite, thorace, 

 pedibus antennisque rufo-testaceis, elytris plus minusve nigricantibus ; capite parvo, 

 oculis magnis ; prothorace trans verso, elytris angustiore, lateribus subsinuatis, 

 fortiter punctato ; elytris crebrius fortiter punctatis ; coxis posterioribus fortiter 

 punctatis ; tarsis anterioribus elongatis, gracilibus, unguiculis minutis. Long. 3f, 

 lat. 2 m.m. 



In the male, the two basal joints of the front and middle tarsi are a good deal 

 dilated, so that the third joint appears very slender in comparison to them ; in the 

 female the three basal joints are all very slender and very compressed laterally. 

 The species varies a little, more especially in the colour of the elytra, which are 

 sometimes black, and vary between that colour and obscure reddish. 



South America, and the Antilles ; Santa Rita, August, 18.50, Sahlberg ; Santa Cruz, 10 to 17, 10, 

 1872, Van Volxem ; Porto Rico fide Wehncke. 444. 



II. 5. — Group L.\cco?niLiNr. 



Sciitellum quite concealed ; front and middle tai'si conspicuously five-jointed ; 

 posterior tarsi with the hind margins of their joints lobed externally ; prosternal 

 process acute behind ; wings of metasternuni very slender, arcuate ; size of the 

 individual small. 



Only two genera are included in the Laccophilini, and one of these (Neptosternus) 

 has yet but a single species, while the other (Laccophilus) has very numerous 

 species. They may be very readily distinguished. 



Prosternal process simply acuminate ; hind angles of thorax ] LAOCOPIIILUS, 

 rectangular or obtuse. j {vide p. 287). 



Prosternal process acutely tridentate ; hind angles of thorax 1 XEPTOSTEIiXUS, 

 elongate, acute. | [vide p. 317). 



