On Aquatic Carnivorous Coleoptent or Bi/tisculce. 707 



oil the wing-cases, consisting of more or less coarse punctures which are scarcely 

 elono-ated, they vary in the extent of their distribution, sometimes extending along 

 half the length of the elytra, but are always widely separated from the outer margiu, 

 and only approach the suture at the base ; the rudimentary claw^ of the posterior 

 tarsi is not much developed and is only to be seen on the underside of the other claw. 



The species is a variable one in size and colour, and in form is most inconstant, 

 being sometimes greatly narrowed in front, sometimes not at all ; it possesses a 

 scattered fine punctuation on the wing-cases, whicli also is variable ; the sides of 

 the thorax are often vaguely ferruginous, but never distinctly yellow. 



It may always be distinguished from the following species by the male front tarsi 

 and hind claws, by the shorter and less slender antennae and by the deflexed lacinite 

 of the hind coxae being nearer to the epipleurse, the female moreover has its sexual 

 sculpture tending to spread less towards the outer margin of the wing-cases. 



Soutli America, (Buenos Ayres, Monte Video, Uruguay, Entee Rios, Parana). 1102. 



Group 3. 



1106. Dytiscus Isevigatus, 01., Tragus Icevigalus, M.C. — Ovahs, sat latus et con- 

 vexus, supra olivaceo-niger, capite auterius prothoraceque ad latera anguste testa- 

 ceis, elytris versus apicem plus minusve vage ferrugineo-tinctis vel submaculaiis ; 

 subtus nigricans, pedibus quatuor anterioribus rufis, posterioribus piceis; antennis 

 gracilibus. Long. 21i, lat. 12i m.m. 



The male has the anterior tarsi small, attaining 2 m.m. in the transverse direction, 

 their claws are only moderately elongate, and are therefore not conspicuously 

 unequal in length ; on the undersurface the palettes are rather narrow, the basal 

 fringing hairs are rather fine and moderately short, and at the heel diverge much 

 from the palettes, so that a distinct pubescent area is formed ; the intermediate 

 tarsi are rather slender, and the three basal joints bear beneath an elongate sexual 

 pubescence, and on the fourth joint there is a less conspicuous development of such 

 pubescence. The female has usually a distinct though not extensive sexual sculp- 

 ture on the base of the elytra ; this sculpture consists of elongate punctures, which 

 at the extreme base extend from the scutellum to quite near the lateral margin, 

 they do not extend, however, more than one-third of the way to the apex, diverge 

 greatly from the suture as they proceed, and also to a less extent from the lateral 

 margin. On the hind tarsi of the male the inner claw is quite as long as, or even 

 longer than, the outer one, while in the female this inner claw remains rudimentary, 

 and is only to be perceived by examining the undersurface of the other claw, to which 

 this rudimentary one remains closely applied. 



This species is variable, but it is possible that some of what I have considered 



TRANS. ROT. DUB. SOC, N.S , VOL. II. * T 



