610 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



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 nan-ow 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. 



o 



Arabia, (El Hedjaz, Dr. MUlingen). 874. 



926. Dytiscus signatus, Fab., -R/ja?i<MS signalus, M.C. — Ovalis, haud convexus, 

 nitidus, subtus niger, prosterno rufo, antennis pedibusque testaceis, pedibus 

 posterioribus magis obscuris, supra testaceus, vertice rufo nigroque variegato, 

 thorace in medio macula fusca plus minusve traiisversim extensa, elytris creberrime 

 nio-ro-irroratis, tarsis posterioribus minus elongatis, articulo quarto inferne leviter 

 posterius lobato-producto, unguiculo interno quam externo duplo longoire. Long. 

 10, lat. 5 m.m. 



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 

 maro-inal 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 slightly 

 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 jn-osternum 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 Ajtcs, Chili, Peru). 875. 



