696 On Aquatic Carnivorous Coleoptera or Dytiscide. 
narrowed in front, and has the epipleure broader. The two individuals I have 
seen differ slightly from one another, the outline of the North American individual 
is a little different from the East Siberian specimen. 
Eastern Siberia, (Amurland) ; North America, (Red River). 995. 
1091. Dytiscus zonatus, Hoppe, Hydaticus 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 haud attingente, fascia posteriore lateraliter ante angulum 
posteriorem desinente ; elytrorum epipleuris angustis. Long. 14, lat. 7% 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 undersurface 
of the middle feet is under examination, the variation in number of these palettes 
causes a different appearance in different specimens; when there are only sixteen 
palettes, they are arranged in two longitudinal series of seven each, the inner 
series being quite regular, while the outer series is rendered a little irregular by 
the 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 irregular, and in those specimens where the total 
number is greatest (19 to 22), even the inner series becomes irregular, so that the 
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 
epipleurze 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 
