ocr. 1768 MARINE ANIMALS 17 
yet been described according to Linneus’s system, so called 
it Larus crepidatus. Its food here seems to be chiefly 
Helices, on account of its dung being of a lively red colour, 
much like that which was procured from the shells. 
12th. A shark, Squalus carcharias, Linn., taken this morn- 
ing, and with it two pilot fish. JI went out in the boat 
and took several blubbers. The pilot fish, Gasterosteus ductor, 
Linn., is certainly as beautiful a fish as can be imagined ; it 
is of a light blue, with cross streaks of darker colour. It is 
wonderful to see them about a shark, swimming round it 
without expressing the least signs of fear; what their 
motive for doing so is, I cannot guess, as I cannot find 
that they get any provision by it, or any other emolument, 
except possibly that the company of the shark keeps them 
free from the attacks of dolphins or other large fish of 
prey, who would otherwise devour them. 
The blubbers taken to-day were Beroe labiata and mar- 
supialis, Mss., the first of which made a pretty appearance 
in the water by reason of its swimmers, which line its side 
like fringes, and are of a fine changeable colour; and 
Callirrhoe bivia, Mss., the most lifeless lump of jelly I 
have seen; it scarcely seems to be possessed of life, but for 
one or two motions we saw it make. ; 
13th. A shark taken, but not one pilot fish attended 
it, which is rather uncommon, as they are seldom without 
a shoal of from ten to twenty. At noon I went in the 
boat, and took the Sallee man, Phyllodoce velella, Linn., which 
is a sailor, but inferior in size to the Portuguese man-of- 
war, yet not without its beauty, chiefly from the charming 
blue of the lower side. Its sail is transparent, but not 
movable, so it trusts itself to the mercy of the winds, 
without being able to turn to windward, as the Portuguese 
man-of-war perhaps can. We saw several of these latter 
to-day, and observed many small fish under their tentacula, 
which seemed to shelter there, as if with its stings it could 
defend them from large enemies. 
15th. I had the good fortune to see a bird of the shear- 
water kind, which I shot; it proved not to have been 
Cc 
