(677. ) 
XXVII.—The Tardigrada of the Scottish Lochs. By James Murray. Communicated 
by Sir Joun Murray, K.C.B., ete.. (With Four Plates.) 
(MS. received April 26, 1965. Read June 5, 1905. Issued separately July 20, 1905.) 
INTRODUCTION. 
Although they are thoroughly aquatic animals, the Tardigrada are not very abundant 
in permanent waters. They are most thoroughly at home in situations where the 
supply of moisture is intermittent, and are therefore conspicuous members of that 
numerous community of animals known as moss-dwellers. They share with the 
Bdelloid Rotifera the power of withstanding dessication. 
Although they have their headquarters in land mosses, many species are quite at 
home in ponds, rivers, and lakes. 
As lacustrine.animals they belong entirely to the littoral region, into which they no 
doubt continually migrate from the adjoining mosses. A favourite habitat is that strip 
of shore between the highest and lowest levels of the lake, the ‘gréve inondable’ of 
Forex. Into this often mossy margin they may migrate in the ordinary way, when the 
loch is low. The next step may be involuntary—the loch rises during floods, and the 
bears, in common with many other animals, find themselves, willy-nilly, converted into 
lake-dwellers. It appears to be certain that of the water-bears introduced into lakes, 
by whatever means, some have found the conditions very congenial. Several species 
7 hitherto been found nowhere but in lakes. 
The condition which renders the margins of lakes favourable to many of the moss- 
haunting animals is, I believe, the thorough aeration of the water resulting from the 
perpetual lapping of the waves upon the shore; the water of the lake in this respect 
resembling running water ; and there are many species of microscopic animals, so sensitive 
to impurity that they are never found in bogs or other stagnant waters, which abound 
in running streams and in the littoral region of large or pure lakes. 
_ No Tardigrade is known to swim—they have no place in the pelagic region of the 
Takes—nor are any of them truly abyssal, though, like so many other animals in 
Scottish lochs, they may extend to considerable depths, and several species have been 
obtained at depths of about 300 feet in Loch Ness. 
The observations of the Lake Survey upon Tardigrades have been chiefly made in 
Loch Ness and Loch Morar. A few collections were made in Loch Treig and one or 
two other lochs, and an examination of these confirms the belief that some of the 
water-bears are characteristic of lake margins. 
' TRANS. ROY. SOC. EDIN., VOL. XLI. PART III. (NO. 27). 100 
