Browne: The Aquatic Coleoptera of the Isle of Man. 159 
The Manx list of species which are not found in the Solway 
list includes four species whose distribution does not reach 
Scotland, viz., N. sparsus, G. urinator, C. walis, and B., affinis. 
The other four species have all been found farther north, so 
that we may regard their absence from the Solway list as 
perhaps temporary. 
The difference between the Manx fauna and that of N. E. 
Ireland is even greater than that between it and the Solway list, 
as four of the species in the third list have not occurred anywhere 
in freland and eight others have only been taken in the south or 
west. Of the remaining two, A biguttatus has occurred only 
once., 7.e., in Armagh, while H. atricapilla is a great rarity, 
having only been recorded from Derry, Armagh, and Cork, E. 
The relationship of the Manx water beetle fauna is therefore 
much closer with N.W. England, than with either S. W. Scot- 
land, or N.E. Ireland, and if present distribution is any indica- 
tion of origin this fact is of considerable importance. 
Unfortunately I have no list of species for Anglesey, and 
my lists for North Wales are much too scanty to be of any 
use, but, as I shall endeavour to show later, there are good 
reasons for doubting whether the Manx fauna came from this 
quarter. 
I have already quoted Dr. Bailey’s opinion that the Manx 
fauna has in part originated from Ireland. Professor Carpenter 
also adopts this attitude. He says*: ‘ The fauna of the Isle 
of Man resembles on the whole that of Ireland, western Eng- 
land and Wales. Its cliffs form the most northern station for 
‘certain species of moths, e.g., Dianthecia luteago, var. barrettii, 
D. cesia and D. capsophila, some of which are scattered along 
the western British and eastern and southern Irish coasts as 
far as Land’s End and Dingle Bay. If the Isle of Man could 
not have supported any fauna during the height of the glacial 
period, we are forced to the conclusion that its shores must, 
since then, have formed part of the northern coasts of a gulf 
opening to the south, down to St. George’s channel.’ 
Both these authors, therefore, hypothecate a land-bridge 
connecting the Isle of Man with Ireland, as well as one connec- 
necting it with N.W. England, and both believe that these 
bridges supplied the fauna and flora to the island after the 
glacial period. 
Now the chief resemblance between the Manx and Irish 
faunas seems to be that both lack a number of species found in 
Britain, species belonging to what has been called the ‘ Siberian ’ 
‘or ‘ Germanic’ type, and such a resemblance does not require 
the assumption of a land-bridge. Indeed Dr. Scharfft makes 
* The Problems of the British Fauna, ‘ Nat. Science’, xi., 1897, pp. 
375-386. : 
{ History of the European Fauna, 1899, p. 123. 
agri April 1. 
