696 On Aquatic Carnivorous Coleoptera or Dy/iscidcp. 



narrowed in frtuit, and has the epipleura; broader. The two individuals T have 

 seen differ slightly from one another, the outline of the North American individual 

 is a little ditferent from the East Siberian specimen. 



Eastern Siberia, (Ainurland) ; North America, (Red Kiver). 995. 



1091. Dytiscus zonatus, Kop-pe, Hydaticns zonatus, M.C. — Sat convexus, nitidus, 

 testaceus, capite vertice signaturisque frontalibus, prothoraceque fasciis duabus 

 nigris, elytris creberrime nigro-vermiculatis ; prothoracis fascia nigra anteriore 

 marginem anteriorem baud attingente, fascia posteriore lateraliter ante angulum 

 posteriorem desinente ; elytrorum epipleuris angustis. Long. 14, lat. 7f m.m. 



In the male of this species there are, besides the threelarger palettes, 32-35 smaller 

 ones on the front feet; and on the middle feet 16 to 22 ; when the undersmface 

 of the middle feet is under examination, the variation in number of these palettes 

 causes a different appearance in diffei'ent specimens ; when there are only sixteen 

 palettes, they are arranged in two longitudinal series of seven each, the inner 

 series being qiiite regular, while the outer series is rendered a little irregular by 

 tlie appearance of two more external palettes, for which there is obtained space by 

 a disarrangement of the outer series ; as the total number of palettes increases, 

 this outer series becomes more irregulai", and in those specimens where the total 

 number is greatest (1 9 to 22), even the inner series becomes irregular, so that tiie 

 biserial arrangement is scarcely to be detected. 



The species is a variable one in other respects. Although the anterior black 

 thoracic band always leaves a space in front of it yellow, yet in some individuals 

 this is not so perceptible as in others; the posterior band too is sometimes thicker 

 (in the antero-posterior direction) than it is in other cases, and although generally 

 it leaves a very slight band behind it yellowish, yet sometimes it extends quite to 

 the hind margin ; in the lateral direction, however, it never extends so far as the 

 angles, indeed it does not reach quite so far laterally as the anterior band does ; 

 the specimens in which the black thoracic bands are most extensive, are generally 

 broader and flatter than the more ordinary individuals, and it is also generally in 

 such individuals that the number of palettes on the middle feet attains its 

 maximum. The shorter and broader individuals with largely developed thoracic 

 black bands greatly resemble Dytiscus cinereus, but may be distinguished by the 

 front black band never quite touching the front margin, while the posterior band 

 always leaves off quite decidedly at some distance inside of the hind angles ; the 

 epipleurse too are a little narrower ; the males are readily distinguished by the 

 supernumerary palettes of the middle feet, as well as by the characters mentioned 

 above. 



The females have a very slight development of additional punctuation near the 

 outer sides of the wing-cases, and they also possess some corrugations near the 



