On Aquatic Carnivorous Coleoptera or Dytiscide. 697 
sides of the thorax ; in certain individuals these corrugations become coarse and 
deep, and in the most extreme cases are accompanied by a radial corrugation on 
the disc of the thorax ; these extreme females were considered by Aubé to be the 
males of Dytiscus verrucifer, Sahl. 
Europe and Siberia; (Sweden; Finland to 67°, Sahlberg ; Germany, Belgium, Northern France, 
Piedmont). 996. 
1092. Dytiscus verrucifer, Sahl., Ins. fern., p. 159.—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. 15, lat. 8? m.m. 
In the male of this species the front tarsi bear about fifty-six smaller palettes, 
besides the three larger ones; the intermediate feet have thirty-six palettes arranged 
in an irregular manner. 
The female has the whole of the upper surface of the prothorax}traversed by 
deep ruge or corrugations, which have a somewhat radiate arrangement on the 
disc : the elytra, too, are covered with very deep furrows, which cause the surface 
to appear densely packed with flattened tubercles ; these tubercles are more or less 
elongate or confluent in the longitudinal direction. 
This insect differs from Dytiscus zonatus by the greater number of palettes on 
the front and middle feet, and by the peculiar sculptute of the female; the under 
surface and the posterior tarsi are sometimes a little infuscate or piceous; and the 
colour of the wing-cases appears more obscure, owing to the black vermiculations 
being thicker so that the yellow specks are more reduced than in D, zonatus. 
Finland, Sweden, Lapland, and Siberia. 997. 
1093. Graphoderes piciventris, Thoms. (ex parte), Sk. Col. X, p. 351.—Sat 
convexus, nitidus, testaceus corpore subtus ex parte infuscato, capite vertice 
signaturisque frontalibus nigris ; prothorace ex parte majore nigro, medio lateri- 
busque testaceis ; elytris testaceis creberrime nigro-vermiculatis, punctis testaceis 
obseuris ; epipleuris angustis. Long. 154, lat. 9§ m.m. 
In the male of this insect there are about 74-80 small palettes, besides the three 
larger ones, on the undersurface of the front tarsi, the intermediate feet present a 
broad sole bearing about 42-52 palettes. The female has the whole of the upper- 
surface of the prothorax traversed by very deep rugz or corrugations, assuming 
a radiate arrangement on the disc: the elytra bear coarse flattened tubercles which 
are quite isolated from one another, and have no tendency to be confluent in the 
longitudinal direction. 
