112 Mr. F. Balfour-Browne on the 



II, fuviatilis, gives its distribution as including "Prussia, 

 Ponierania, Silesia, and Moravia," and says it is " not rare/' 

 lleitter apparently knew Thomson's species, because he sent 

 nie Norwegian specimens of it, and he must therefore have 

 meant something else by str'iatus. Zaitzev (23) describes 

 strialus as a variety of f/uviatilis, and ?ays that it occurs in 

 the St. Petersburg district; but he makes no mention of 



Only two authors, so far as I am aware, have in any way 

 connected the two names. Seidlitz (17) mentions '^ striatus, 

 Wehncke," and in a footnote says that striitus, Sharp, is not 

 determinable, as the description dates from a time when only 

 two or three species of the rujicolUs group were separated ; 

 and this although the types are in existence and tlie author 

 is still living ! In the range of this species Seidlitz includes 

 Sweden, but he adds a note in which he says that the Swedish 

 specimens were sent as //. apicaUs, Thomson, but are without 

 the characteristics which Thomson attributes to that species. 



I can find nothing in Thomson's description which does 

 not apply to Sharp's species and nothing in Sharp's descrip- 

 tion which will not suit Thomson's species; but, apart 

 altogether from these descriptions, the specimens sent me as 

 apicaUs both by Ganglbauer and by lleitter, and which came 

 from Borkum Island, Norway (Christiania and Tromso), and 

 Sweden, agree in every respect with my examples oi II. stria- 

 tus, -which agree with specimens of this latter both in 

 Dr. Sharp's collection and in that of the late Wm. Lennon, 

 of Dumfries, who also took the species in the original 

 locality. 



The other author who associates the two names is Lucas 

 von Heyden (10), who actually gives striatus as a synonym 

 of apicaUs ! 



Of course, 1 have not seen Thomson's type-specimens, and 

 am only relying upon Scandinavian specimens received from 

 two independent sources. 



In the Britannic area //. apicaUs is confined to coastal 

 waters and is practically a brackish-water species. Thomson 

 says that he took it in brackish water. If Heyden's identi- 

 fication is correct, a single specimen has occurred inland at 

 Frankfurt, and it is quite possible that the species may occur 

 normally inland on the continent, as otlier species, which witii 

 us are confined to brackish water, are found under better 

 conditions on the mainland of Europe (e. g,, Laccophilus 

 variegatuSj Germ., Coilamhus parallelogrammus, A\\x., PJiil- 

 hydrus maritimus, Thorns., &c.). 



The species is apparently very local in our islands, though 



