A GUIDE TO THE STUDY OF BRITISH WATERBUGS. 203 



is therefore evident that paludum auctt. is synonymous with 

 najas, De Geer ; while najas auctt. must take the name of 

 canalium, Dufour,* the next name available. The synonymy 

 will be : — 



1. Canalium, Duf. (type of subgenus). 



Cimex lacustris, Sulzer, 1761 = " species allied to C. najas," 

 De Geer (Mem. iii., pi. xvi., figs. 8 and 9), 1773 — C. najas var. 

 a apterus, Eetz., 1783 = A. paludum, Schell., 1800 = G. aptera, 

 Schumm., 1832 = G. canalium, Duf., 1833 = G. pausarius, 

 Curt., 1835 = H. Najns, Fieh,, 1861 = G. najas of modern 

 authors. 



2. Najas (De Geer). 



Cimex najas, De Geer, 1773, I. c, pi. xvi. fig. 7 = C najas 

 var. B alatus, Eetz., 1783 = G. paludum, Fabr., 1794, and 

 modern authors. 



In G. canalium the connexival spines do not project so far as 

 the apex of the abdomen. The apical segments of the venter are 

 represented on plate iii.f fig. 15 $ , fig. 16 ? ; plate i. fig. 7 re- 

 presents an antenna ; plate i. fig. 11, the sterna. 



This species is nearly always apterous, and I have seen it 

 only in this condition. It is sometimes fairly abundant locally, 

 though it can scarcely be considered common. It is well distri- 

 buted over the southern English counties ; but I know of only a 

 single record (Lincolnshire) north of the Thames, and none from 

 Scotland or Ireland. 



In- G. najas (De Geer), Kirk., the connexival spines project 

 so far as, or a little farther than, the apex of the abdomen. It is 

 rather larger than the preceding species, and is nearly always 

 macropterous. I have seen brachypterous, but not apterous, 

 individuals. 



Figs. 17 and 18 represent the apical segments of the venter, 

 male and female, respectively. 



It is fairly well distributed, though common only locally, 

 perhaps. Cardiff, Cowbridge and Ipswich are the only localities 

 north of the Thames known to me. 



(/3) Limnoporus, Stal, 1868. 



There is only a single species, G. rufoscutellatus (Latr.), 

 which has been recorded from three or four localities only, 

 widely apart, from Pitlochry to Hastings. It has a very wide 

 distribution; the records of "rufoscutellatus" from Europe, 

 Siberia, Turkestan, and North America all apparently referring 

 to one species. 



:;: I have grave doubts as to the validity of the name "najas" at all, 

 since De Geer, although mistakenly, refers it to the same S] ecies as lacustris 

 Linn. 



f This plate will be issued with a future number of the ' Entomologist.' 



