532 On Aquatic Carnivorous Coleoptera or Dytiscide. 
Maes, nitidus, elytris fusco-zeneis, elytrorum reticulis sat elongatis. Long.12 m.m. 
Fem., opaca, elytris fusco-sub-rufis, ad apicem sat nitidis, subtilius reticulatis, 
reticulis elongatis, tantum ad apicem latioribus et brevioribus. Long. 11 m.m. 
The male has the three basal joints of the front and middle tarsi incrassate, and 
furnished beneath with glandular hairs, the outer portion of which bear about three 
series of ill-developed palettes; the claws of both feet are rather elongate, equal and 
simple : the sexual difference in sculpture and appearance is very striking. 
Though the species is approximated by the various varieties of Dytiscus bipus- 
tulatus, yet on the whole it seems to me that it must be considered a distinct 
species, until sufficiently intermediate forms can be brought forward. The simple 
structure of the male tarsal claws, is a prominent distinctive character ; the female 
is excessively close in appearance to the 9 var. (Agabus solieri, Aubé). of A. bipus- 
tulatus, but it has not the sides of the thorax rounded ; in both sexes the prosternal 
process is rather broader and flatter than in Dytiscus bipustulatus, approximating 
to that of Agabus melanarius, Aube. 
Madeira. 806. 
751. Dytiscus bipustulatus, Linn., Agabus bipustulatus, M.C.-—Species per varia- 
bilis; supra et infra undique strigulosus, niger, supra plus minusyve enescens, 
antennis palpisque rufis, pedibus piceis, anterioribus dilutioribus ; reticulis elytrorum 
semper in parte basali longitudinalibus, seepius angustis et elongatis. Long. 10, 
lat. 55 
The male has the three basal joints of the front and middle tarsi much incrassate, 
and furnished beneath with glandular hairs, the outer portion of which bear about 
three rows of ill-developed palettes; a considerable portion of the basal joint on 
the front feet is bare. The anterior claws are unequal, the front one being moderately 
long, and bearing a small tooth beneath at the extreme base, while the hinder one 
is elongate and much dilated behind, the swelling extending over the greater part of 
the length of the claw but leaving the extremity slender, and causing the outline 
behind to be much sinuate: the claws on the middle feet are also unequal, both are 
elongate and very little curved, the anterior one being considerably longer than the 
other. There is generally a sexual difference in the sculpture of the upper surface 
the female being duller than the male, and having the longitudinal striz finer and 
denser, and on the humeral portion taking a more oblique outward direction, the 
sculpture at the extreme apex is the same as in the male. 
This species which is perhaps the commonest of the European Dytiscidee 1s 
extremely variable as regards size, colour, form, sculpture, sexual disparity, and 
the form of the male tarsi: the broad supra articular border readily distinguishes 
it from the other European allies, except A. melanarius, Aubé, and that species always 
