On Aquatic Carnivoo'ous CoJeoptera or DytiscidcB. 893 



at present to attempt a natural classification of them, based on the whole of their 

 structures. The peculiar sculpture of the wing-cases offers however a very simple 

 means of arranging the species in groups, and I have accordingly made use of it, 

 and classed the species in fourteen groups. Seven of these groups have, in addition 

 to the conspicuous strise, a submarginal stria placed very near the outside of the 

 wing-case, quite close to the irregular punctures near the epipleural margin ; this 

 stria is of variable length, sometimes quite short; in groups 1 to 7 no trace of it 

 exists. 



I. 55.— Genus A GL Y2JB US. ( Vide p. 596.) 



This aggregate is formed by seven species ; they are similar in most respects to 

 Copelatus, and possess on the upper surface a beautiful and conspicuous sculpture 

 of very short lines. The hind coxse are very large ; the wing of the metasternum 

 terminates as a slender band abruptly deflexed outside the front part of the coxa ; 

 the coxal lines are quite obliterated, the coxal lobes are shaped as in Copelatus 

 and possess a well marked incision. 



The aggregate is allied to Copelatus, differing from it in the obliteration of the 

 coxal lines ; all the species, except A. brevicornis, have the spaces which should be 

 included between them (if they were not obliterated) broader than in Copelatus ; 

 A. brevicornis departs however from the other species in this respect and is similar 

 to Copelatus by the excessive reduction of these spaces. It is highly probable 

 that this species, and probably also A. gestroi, should be separated from the 

 others ; and even then it is possible that the remaining South American species 

 could not properly be included in one genus. The sjjecies are howevei- so exces- 

 sively rare, that of most of them 1 have seen only a single individual, and in 

 several cases 1 have no specimen now before me for comparison and verification 

 and have merely to trust to the imperfect notes made when I dre\vf up the descrip- 

 tions of the species. 



The following additional characters are drawn from Agabus rufipes Auhi : — 

 Prothoi'ax veiy finely margined. Middle coxae rather closely approximate ; im- 

 pression on the apex of intra-coxal process of the metasternum short and indefinite. 

 Hind femora rather stout, with well marked lamina at extremity, without acumu- 

 lated setse near this angle ; hind tarsi rather elongate and slender, terminated by 

 two rather small nearly straight and equal claws. Male front tarsi strongly 

 compressed. Sculpture of the upper surface consisting of short impressed straight 

 lines. 



In this species the basal joint of the hind tarsus is feebly lobed externally, and 

 the following joints are destitute of lobing. While in Agabus leprieuri (No, 898) 

 and Aglymbus sculpturatus, the four basal joints are strongly lobed ; and in these 

 two species the male tarsi are nearly simjile, and the sculpture of the upper surface 



6 V 3 



