1885.] COLEOPTERA FROM JAPAN. 193 



I can only compare this species with D. sulcicollis, from North 

 America, to which it is certainly closely allied. The thorax is, 

 however, much more narrowed behind than in that species and the 

 anterior callosities are much more developed ; another difference is 

 to be found in the more elongate joints of the antennae and thfir 

 comparative different length. Z). discolor, Hoppe, may be at once 

 distinguished from the jiresent insect by the more opaque and con- 

 fluently punctured thorax ; the latter in D. constricticoUis having 

 a highly polished appearance. 



DoNACiA SERiCEA, L., var. siBiRiCA? Solsky. 



The dozen specimens obtained at Nikko show scarcely any 

 difference from our European form ; but may very well be referred to 

 Solsky's variety according to the description given by this author. 

 In colour the specimens vary from reddish cupreous to green or 

 seneous like the European D. sericea. Structural differences I can 

 see none. 



DoNACIA SIMPLEX, Fab. 



Of this species Mr. Lewis obtained nine specimens at a pond at 

 Hakodate. They also, like the preceding species, do not differ from 

 the European form in any way whatever, and vary in size like it ; 

 D. simplex has also been recorded from Siberia. 



Genus Syneta, Eschsch. 

 Syneta adamsi, Baly. 



Of this species, of which I have the tj'pe for comparison, several 

 specimens were obtained by Mr. Lewis which agree very nearly with 

 the latter ; but a number of others, partly from the same locality, 

 seem at first sight certainly to represent a different species ; and I 

 have hesitated long before I came to a conclusive opinion in regard 

 to their specific value. The very many intermediate forms, however, 

 of which scarcely two are of the same size, sculpturing, and colour, 

 which are before me, prove the insect to be an extremely variable 

 one. On the same principle I am very much inclined to believe that 

 those species described by LeConte from America, established 

 principally on colour and more or less distinctly visible elytral costse, 

 may eventually prove to belong to one species only. At all events, 

 the specimens collected by Mr. Lewis defy a satisfactory separation : 

 in some the thorax is much more elongate than is the case in 

 S. adamsi, but intermediate stages are not wanting ; in others two 

 very distinct costse are visible, these dwindling away again to the 

 form with one distinct lateral costa only, as described by Baly. The 

 thorax in all of them is like that of the type, angulateat the middle, 

 the angle itself generally 3-dentate, in some specimens the in- 

 termediate tooth being only distinct, the others obsolete. The 

 following are the varieties with their localities : — 



Var. a. Head and thorax as well as the terminal joints of the 

 antennae fuscous or black ; elytra with a sutural and lateral broad 

 longitudinal fuscous band. (Niohozau, Kiga, on birch.) 



Proc. Zool. Soc— 1885, No. XIII. 13 



