610 On Aquatic Carnivorous Coleoptera or Dytiscida. 
The male has the basal joints of the front and middle tarsi a little incrassate and 
extremely compressed, and furnished beneath with four rows of narrow elongate 
palettes, the marginal hairs are but little developed ; the claws on the front foot 
are moderately long and slender, and are nearly equal and simple, the front one 
being obscurely bisinuate beneath ; the claws of the middle feet are nearly as long 
as those of the front feet, and are simple and equal. 
Although closely allied to Colymbetes pulverosus, this is an undoubtedly distinct 
species, it is rather more convex, and has the hind legs thicker and shorter, and the 
male anterior claws much longer. 
Arabia, (El Hedjaz, Dr. Millingen). 874. 
926. Dytiscus signatus, Fab., Rhantus signatus, M.C.—Ovalis, haud convexus, 
nitidus, subtus niger, prosterno rufo, antennis pedibusque testaceis, pedibus 
posterioribus magis obscuris, supra testaccus, vertice rufo nigroque variegato, 
thorace in medio macula fusca plus minusve transversim extensa, elytris creberrime 
nigro-irroratis, tarsis posterioribus minus elongatis, articulo quarto inferne leviter 
posterius lobato-producto, unguiculo interno quam externo duplo longoire. Long, 
LO @latarommaymne 
The male has the basal joints of the front and middle tarsi a little incrassate, 
and very compressed, and furnished beneath with four rows of narrow palettes, the 
marginal hairs are but little developed ; the claws on the front feet, are slender 
and rather elongate, the anterior one is obscurely bisinuate beneath, and is shghtly 
longer than the other ; the claws on the middle feet are are not so long as those of 
the front feet, and are rather slender, the inner one being a little shorter and more 
curved than the outer. 
This species is excessively similar to Colymbetes pulverosus (No. 924) but is 
smaller, and has the prosternum paler, and the male front claws longer; it is 
smaller than R. elevatus, and has the claws on the hind tarsi, more especially the 
outer one, shorter. 
This species varies considerably in size, and in the black colour of the upper 
surface ; the dark mark of the thorax is in small narrow individuals generally 
extensive, and the black dots of the elytra close and more or less confluent; in 
very broad individuals the thoracic mark sometimes becomes so indistinct that it is 
represented only by two small fuscous spots close to one another on the middle of 
the thorax, and in these individuals, the black dots or irrorations on the elytra are 
more sharply defined. I can find no trace of a division into two species. ‘There is 
an individual in my collection in which the claws of the right hind foot are sub- 
equal in length, those of the left foot being of the form general in the species. 
South America, (Monte Video, Buenos Ayres, Chili, Peru). 875. 
