THE AQUATIC COLEOPTERA OF THE MID-EBUDES 79 



seemed to be suitable ground, failed to produce either 

 Coslanibus g-lineatus, Steph., or Deronectes depressus, F. 



The halophil fauna is apparently absent from Coll. In 

 the brackish pools in the sea-turf at Aringour, Hydroporus 

 lituratus, F., and planus, F. ; Anaccena globulus, Payk. ; 

 Helopliorus aquaticus, L., and viridicollis^ Steph., were the only 

 species present, and these are all tolerant of salt but not 

 dependent upon it. I have felt inclined on several occasions 

 to treat H. planus as a halophil, since in the Sol way district 

 and several other places it is very abundant in the brackish 

 pools in company with such typical halophils as Agabus 

 eonspersus, Marsh ; HelopJiorus dorsalis, Marsh ( == mulsanti, 

 Rye) and Octhebius marimts, Payk., but the species occurs 

 equally commonly in brick-clay holes, e.g. in the Clyde area, 

 often as the dominant species, from which it appears that 

 the fine mud of the brackish pools rather than the salt is 

 what attracts it to these. 



The species confined to the east coast of England and 

 Scotland are, as is to be expected, absent from the Mid- 

 Ebudes, but both the northern and southern groups are 

 represented there. With regard to the northern group 

 Deronectes griseo-striatus, De G., was taken by Dr. Power in 

 Mull, and Dytiscus lapponicus, Gyll. ; Agabus arcticus, Payk. 

 and congener, Payk., Hydroporus morio, Dej., etc., all occur on 

 Mull, but, being mountain species, they are not found in Coll. 

 Ilybius (znescens, Thorns., and Hydroporus nielanarius, Sturm., 

 which are probably northern in origin, both occurred very 

 sparingly on Coll. The southern group is represented by 

 two interesting species : Paracymus nigroczneus, Sahib., I 

 found several times on Coll and Mull, and it also occurred 

 in Argyll Main near Oban. Its distribution in England is 

 southern and western, and in Ireland also it only occurs in 

 the south and west. It is a peat-moss species occurring 

 among Sphagnum in the peat holes. In Mull it occurred 

 up to about 300 feet above sea-level, but in the west of 

 Ireland I found it at rather higher altitudes although it could 

 not be called a mountain species. So far, I have failed to 

 find it in the Solway district, which is peculiar, especially as 

 so many other southern species occur there. 1 



1 'Coleoptera of the Solway district,' "Ann. Scot. Nat. Hist." 1909. 



