On Aquatic Carnivorous Coleoptera or DytiscidcB. 621 



952. Rhantus latitans, n. sp. — Ovalis, parum convexus, testaceus, vertice nigro- 

 variegato, elytris nigro-irroratis, prothorace basi in medio brcviter nigricante ; tarsis 

 posterioribus articulo quarto extus lobato-producto. Long. 10 J, lat. 5| in.m. 



The male has the front tarsi moderately incrassate and a good deal compressed, 

 and furnished beneath with rather small palettes, the marginal hairs but little 

 developed, the claws are only moderately long and slender, the hinder one slightly 

 shorter than the other ; the middle feet are clothed beneath in a similar manner to 

 the front feet, their claws are rather short, the thickened outer one being scarcely 

 longer than the inner one, this, however, is more curved at its termination ; there is 

 not the least trace of any strigosity in the middle of the apical part of the last 

 ventral plate. 



This species is extremely closely allied to that preceding, with which it is always 

 mixed in collections, the male has the front and middle claws much shorter, and 

 the tarsal palettes rather smaller ; the females are not so easily distinguished, but 

 the constant black mark at the base of the thorax, and the smoother apical ventral 

 segment, allow it to be recognized ; there is also a slight difference in the form, 

 which is generally narrower in front in the present species, and the produced lobe 

 on the fourth joint of the hind tarsus is a little broader and shorter, and the longer 

 of the two posterior claws is a little shorter and thicker. The female has generally 

 a slight tendency towards a coarser reticulation near the outside of the elytra about 

 the middle. Whether this be really a distinct species from the preceding is doubt- 

 ful, for none of the characters except that of the male claws appear to be constant, 

 and the females are always very difficult to distinguish. 



Europe, (Germany, Belgium). 899. 



953. Colymbetes consputus, Sturm, Rhantus conspiitus, M.C. — Ovalis, sat con- 

 vexus, nitidus, testaceo-ferrugineus, vertice nigro-variegato, elytris nigro-irroratis. 

 Long. Hi, lat. 61 m.m. 



The male has the front tarsi much incrassate and comparatively little compressed, 

 and furnished beneath with large palettes, the marginal hairs largely developed and 

 with beautifully curled extremities, the claws are moderately long, and very nearly 

 equal in length ; the middle tarsi are clothed beneath in a similar manner to the 

 front feet, their claws are rather short and of about equal lengths, the outer 

 however is thicker than the more curved inner one ; the apical venti'al segment is 

 quite smooth along the middle ; the female has the outer portion of the elytra more 

 coarsely reticulate especially about the middle, the apical ventral segment has the 

 extremity quite smooth in the middle. 



The species is readily distinguished from D. exoletus and R. latitans, by its 

 greater size, and by the greater development of the male tarsi. 



Europe, (Germany). 900. 



i L 2 



