Browne: The Aquatic Coleoptera of the Isle of Man. 133 
porus rivalis, nor is there a Manx record for it. It is difficult to 
account for its absence as it is recorded from England, Scotland, 
and Ireland. With regard to its British distribution there 
seem to be a fair number of counties in the south and south- 
east of England in which it has not occurred, and from its 
present known British distribution, I think it may be regarded 
as belonging to Watson’s ‘ Scottish’ type* which includes species 
showing a concentration in the north of England and south of 
Scotl>nd. Of the ten species which, from their present knowr 
British distribution may be referred to this type, five others are 
apparently absent from the island, viz., C@lambus 9-lineatus, 
Deronectes assimilis, Agabus affinis and unguicularis and 
Acilius fasciatus, so that the type is poorly represented. Of 
these, the first two are lake species, while the third and fifth 
may be described as ‘lowland oxylophils.’ Lowland peat 
moss is not common on the island, and I only visited three 
localities—(1) ‘ The Curragh,’ which at one time was perhaps 
a good ground, but is now rather barren. Here I took the 
only specimen of Hydroporus obscurus ; (2) a small area near 
Ballaugh, detached from the Curragh, where Sphagnum 
flourishes. Here Helochares punctatus and Copelatus agilis 
were abundant. The former only occurred on this ground, but 
I took one specimen of the latter in another place; (3) at 
Foxdale, where a pond, covered with Equisetum and surrounded 
with thick Sphagnum yielded Gyrinus minutus, Ilybius e@nescens 
and Rhantus bistriatus among the species. This was the only 
place I found the first two species, and they were very common. 
A single specimen of Jlybius swbeneus turned up in a pond 
near Andreas. The only other British records for this species 
are Lincs. N., Norfolk E. and W., Cambs., Suffolk.E., Surrey 
and Kent W., but it has a wide range elsewhere from N. America 
to Siberia. In England, as in the Isle of Man, I have always 
taken it in drains or ponds with the group of ‘helophils’ or 
fresh-water marsh species, but in Norway at 3000 feet eleva- 
tion, it was common as an ‘ oxylophil’ or peat moss species 
in company with Dytiscus lapponicus, Agabus arcticus, Ilybius 
angustior and @nescens, etc. 
Of the ‘ helophils,’ the most interesting species was Berosus 
affinis which was common in a farm pond near Andreas. The 
northern plain is the chief centre of this group in the island, 
owing to the scarcity of stagnant water elsewhere. I found 
a single specimen of Gyrinus urinator in a slow flowing drain 
near Sandygate, and there is another specimen in Dr. Bailey's 
collection. It was amongst a series of G. natator, and is 
*It must be remembered that H. C. Watson, in the Cybele Britannica, 
founded his types on the British distribution of the species without any 
reference to the sources from which the plants reached the country. 
igit Mar. 1. 
