water-beetles of Japan. 459 



Cercyon unipunctatus, var. 



Coccinella unipunctata, L., Faun. Suec, No. 470. 



A single example of a variety with remarkably coarse 

 sculpture was found at Tomakomai, August 18th, 1880, in 

 company with a series of the European C. quisquilius. 



Cercyon vagus. 



Ovalis, convexiis, posterius subaciiminatus, nitidus, piceus, supra 

 obscure rufus, hie inde vage piceo-suffusus, antennis jialpisque 

 testaceis, pedibus rufis ; protliorace crebrius sat siibtiliter piinctato, 

 elytris profunde striatis, interstitiis parce obsolete punctatis. Long. 

 2f mm. 



To be placed near C. ustus, but readily distinguished 

 by the deeply striate elytra so that the interstices are 

 convex, and by the obsolete punctuation of these latter, 

 the striae are only obscurely punctured. Only two 

 individuals have been found, and, as the coloration of 

 the surface differs in the two, it is evidently variable, 

 and need not at present be alluded to in detail. 



Found at Miyanoshita in May, 1880, and also at 

 Oyama. 



Cercyon placidus. 



Ovalis, convexus, nitidus, niger, antennis palpisque testaceis, 

 pedibus rufis ; prothorace subtiliter minus crebre punctato ; elytris 

 anterius seriatim punctatis, posterius profunde striatis, interstitiis 

 parce punctatis. Long. 2f mm. 



Black, with the head and thorax picescent, very shining, with 

 quite fine and scanty punctuation on the thorax ; on the elytra 

 there are very distinct series of punctures ; those near the suture 

 are quite fine at the base, but become deep striae behind. 



The species may be at a glance distinguished from 

 C. vagus by the fine thoracic punctuation, and from 

 C. ustus by the elytra being marked with deep striae 

 behind. 



Found atHitoyoshi and Nikko,but only three examples. 



Cercyon aqualis. 

 Ovalis, convexus, nitidus, ferrugineus, supra niger, anterius 

 picescens, antennis palpisque testaceis, pedibus rufis ; prothorace 

 crebre fortiter punctato ; elytris seriatim punctatis, posterius sub- 

 striatis, interstitiis crebre fortiter punctatis. Long. 2^ mm, 



