536 On Aquatic Carnivorous Coleoptera or Dytiscida. 
754. Agabus clavatus, Lec., M.C.—Oblongo-ovalis, sat convexus, fere angustus, 
nitidus, subleevigatus, ferrugineus, antennarum palparumque apicibus fuscis ; 
prothorace fere brevi, margine laterali sat crasso. Long. 8, lat. 4 m.m. 
The male has the five apical joints of the antenne dilated and flattened, and 
when the underface of the joints is looked at each is seen to be somewhat distorted 
or sinuate near the farther inner angle; the basal joints of the front and middle 
tarsi are a little incrassate, and are somewhat amply furnished beneath with rather 
small oval palettes ; the claws are slender and simple, the front one being longer 
than the hind one, and but little curved. The female I have not seen. The upper- 
surface when carefully examined is seen in this species to be sparingly and exces- 
sively minutely punctulate. 
North America, (Kansas). 809. 
755. Dytiscus serricornis, Payk., Agabus serricornis, M.C.—Ovalis, convexus, 
subopacus, ferrugineus, supra fusco-zeneus, limbo plus minusve ferrugineo ; pro- 
thorace elongato, antrorsum fortiter angustato, angulis posterioribus subrotundatis, 
margine laterali haud lato ; elytris opacis subleevigatis. Long. g 11, lat. 6 m.m. 
The male is considerably larger than the female, and has the four apical joints of 
the antenne dilated and flattened, and excavate beneath ; the front femora are 
furnished beneath with long dense cilize ; the hind legs are very peculiar, their 
femora are a little depressed or thinned near the trochanters, the tibize have their 
lower face somewhat curved, and their inner edge densely ciliate, and the basal 
joint of the tarsus has its lower face much curved, and densely ciliate ; the front and 
middle tarsi have their basal joints much incrassate and compressed and amply 
furnished beneath with moderately large, rounded palettes ; the claws of the front 
feet are elongate, slender, and nearly straight. There is no sexual difference of 
sculpture, and when the upper surface is examined, its dullness is seen to arise 
from its being excessively finely and densely reticulate, and it is also seen to be 
excessively minutely and sparingly punctulate. 
North Europe, and Siberia ; (Sweden ; Finland to 69° 40' North, Sahlberg). 810. 
756. Agabus clavicornis, n. sp——Ovalis, sat convexus, subopacus, piceus, supra 
eenescens, antennis rufis; prothorace sat elongato, antrorsum sat angustato, angulis 
posterioribus subrotundatis, margine laterali haud lato ; elytris opacis subleevigatis. 
Long. 102, lat. 6 m.m. 
The male is broader than the female and has the four apical joints of the antennee 
dilated and flattened, and excavate beneath ; the front femora are densely ciliate 
beneath ; the front and middle tarsi are very broad and but little compressed, and 
are furnished beneath with large palettes ; the claws of the front feet are elongate, 
