FAUNA OF THE CLYDE SEA-AEEA. 



443 



should coiitiuue 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 tlie 

 steam-yacht ' 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 H. 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 Can tyre to Corsewell Point in 

 Wigtownshire, almost coinciding with the contour of 50 fathoms ;" 

 and within it he defines seven deep-water basins, which 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 Locb Tyne, being in shape like the 

 letter X. 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 fatlioms. 



2. Upper Loch Ft/ne 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 

 Bothesay, and attains a depth of a little over 40 fathoms. 



* Scottish Geogr, Mag. iii. pp. 1-7 (1887). 

 LINN. JOUEN. — ZOOLOGY, YOL. XX. 33 



