298 THE ENTOMOLOGIST. 



No. 1 seems to be a slenderer species than No. 2, and the 

 first ahtennal segment much shorter in proportion to the head. 

 The male genital segments seem different, and there are one or 

 two minor differences. I cannot see anything in the description 

 of lateralis, Schumm., really discordant with asper, Fieb. ; but, 

 as I do not know which of the two forms above mentioned (if, 

 indeed, they are distinct specifically) is the true asper of Fieber 

 (or the true lateralis of Schummel), I have left the matter in 

 suspense until I can obtain more material. My impression is 

 that there are two species : — 



1. G. lateralis, Schumm., inhabiting Continental Europe 

 (more or less locally), = G. asper (Fieb.) (and G. lateralis (Fieb.) ?). 



2. Gerris, sp. n., inhabiting subalpine Scotland very locally 

 and rarely, = G. asper, Douglas, Scott, and Saunders. 



Fig. 21 represents the sixth abdominal segment (from beneath), 

 &c, of my male from Pitlochry. 



5. G. thoracicus, Schummel. 



= G. plebejus, Horvath. 



A very common species all over England, and probably over 

 the Scottish Lowlands. I have one or two specimens from near 

 Inverness, but it is quite absent from the Highlands proper 

 (being replaced by G. costce), and is rare in Northern Europe. I 

 have never seen an individual in which the rufescent (or flave- 

 scent) colour on the posterior lobe of the pronotum was not 

 distinctly apparent. 



Fig. 22 represents the apical parts of the abdomen in the 

 male ; fig. 23 those in the female (beneath). 



6. G. costce (Schaff.). 



= G.rufoscutellatus, Costa (nee Latreille). 



= G. lateralis, Puton (nee Schummel). 



Very closely allied to G. thoracicus. Its distribution is 

 remarkable. It is not uncommon over the greater part of 

 Central and Southern Europe, but has not ito my knowledge) 

 been found yet in Scandinavia. In the British Isles, on the 

 contrary, it is a subalpine species. It has been recorded from — 

 England, Buxton ; Nokth Wales ; Ireland, Donegal and 

 Armagh ; but apparently only sparingly. In the Highlands of 

 Scotland it is by far the commonest species ; I have taken it 

 from near Callander (in Perthshire) to Inverness, and from Loch 

 Callater (near Braemar) to the Isle of Skye, and it has been 

 noted also from Isle of Harris and the Orkneys. Up to this 

 year I had taken only the melanic form, but this year, in Skye, 

 I found colour varieties very commonly. The most extreme 

 were («) bluish black (the "rufescence" on the posterior lobe 



