FAUNA OF THE CLYDE SEA-AREA. 
443 
should continue these investigations, and endeavour to render 
them as complete as possible during the months of July and 
August, offering at the same time to give me the use of the 
steam-jmcht ‘ Medusa ’ for dredging and trawling, and to allow 
me the use of the materials which he had already accumulated. 
Circumstances fortunately allowed of my accepting this offer, 
and during the two months just mentioned I made Millport, on 
the Island of Cumbrae, my headquarters, and thence made ex- 
cursions to all the different parts of what is now known as the 
“ Clyde sea-area.” 
The physical configuration of this region has been very ably 
described by Dr. Hugh R. Mill *, whose communication is illus- 
trated by an admirable orographical and bathymetrical chart. 
He regards the “ Clyde sea-area ” “ as bounded on the south by 
a line drawn from the Mull of Cantyre to Corsewell Point in 
Wigtownshire, almost coinciding with the contour of 50 fathoms 
and within it he defines seven deep-water basins, w r hich have a 
depth exceeding 20 fathoms, and are separated from each other 
by ridges, considerably shallower than the extreme depths of the 
basins themselves. 
1. The Arran Basin extends on either side of the north of 
Arran, and up into lower Loch Dyne, being in shape like the 
letter A. In the sequel I have regarded it as subdivided into 
four portions, which may be termed respectively the “ Brodick,” 
“ Cumbrae,” “ Kilbrennan,” and “ Inchmarnoch ” basins. 
The last of these is the deepest, and, indeed, attains the 
greatest depth found anywhere in the Firth, namely 107 fathoms 
off Skate Island. The Kilbrennan and Inchmarnoch Basins are 
not so distinctly marked off from each other as are the remaining 
ones, the channel which unites them just reaching the 60-fathom 
line, the extreme depth of the former being 85 fathoms. The 
Brodick basin, which is off the bay of the same name, has a 
depth of 92 fathoms, whilst the Cumbrae basin descends only to 
62 fathoms. 
2. Upper Loch Fyne is 25 miles in length, and has a depth of 
about 80 fathoms off Strachur. 
3. Loch Striven runs up into the mainland due north of 
Rothesay, and attains a depth of a little over 40 fathoms. 
* Scottish Geogr. Mag. iii. pp. 1-7 (1887). 
LINN. JOURN. — ZOOLOGY, VOL. XX. 
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