HYDROPHILID^. 25 



i. Upper side pitch-black, the sides of the 



thorax very narrowly and the apex of the 



elytra paler. Sides of thorax strongly 



curved in the front half, nearly straight 



behind. Punctuation of elytra deeper 



than in A. ovata. Body in the lateral 



aspect higher in proportion to its length, 



the apical slope of the elytra consequently 



more steep ...... A. limbata, Fab. 



ii. Elytra yellow-brown or brownish-yellow : in 



life bearing a common oblong black spot 



just before the middle, and a narrow dark 



sutural stripe, but these markings are 



very fugitive and usually absent in speci- 

 mens which have been long dead. Body 



in the lateral aspect not so high in pro- 

 portion to its length, the apical slope of 



the elytra consequently less steep. 



1. Head black, sometimes with the free edges 



of the forehead narrowly yellow-red ; 

 thorax piceous, with the sides broadly 

 and suffusedly pale ; maxillary palpi 

 with the last joint entirely pitch-black. 

 Sides of thorax evenly and feebly curved 

 throughout. Body in the lateral as- 

 pect higher in proportion to its length 

 than in A. bipitstulaia . , . .A. ovata, Eeiche. 



2, Head black, with a large triangular 



yellow- red spot on each side in front ; 

 maxillary palpi with the last joint suf- 

 fusedly red-yellow for a greater or 

 lesser distance from the base ; thorax 

 brownish -yellow, with three, usually con- 

 tiguous, dusky spots, viz., a i-homboid 

 one in the middle, and one on each side 

 in the shape of a triangle, of which one 

 point touches the base ; the situation 

 of these markings gives the efiect of 

 two pale triangles standing on the 

 base of the thorax, one to the right 

 and the other to the left of the 

 scutellum ... A. bipustulata, Marsh, 



Dr. Sharp's A. variahilis (Ent. Mo. Mag. vi. 1870, 275) has been 

 long dropped as being synonymous with A. limbata, and A. ovata seems 

 to have no more claim to specific rank ; the characters above given for 

 the species are often more or less variable. Mr. Edwards says that 



