136 
BATHYMETKICAL SURVEY OF 
The reservoir did doubtless afford the opportunity, but, as it turned out, it 
would have been necessary to visit it at very short intervals. In January 
there was an almost total absence of life ; in the following July the process 
of stocking was almost completed — if all the kinds of life found in old lochs 
had not arrived, those which had arrived were very well established and 
distributed all through the water. In January, 1906, a few months after 
the reservoir was filled, the temperature was 36° Fahr, at the surface. 
No life whatever was found except a few individuals of a kind of crustacean, 
a Cyclops not of the common species found in lakes. 
“It was not convenient to visit Talla again till July, 1906, when the 
bathymetrical survey was made. The surface temperature was then 56°. 
The three commonest lacustrine Crustacea were present — Daphnia hyalina 
was scarce ; Cyclops strenuus was abundant, but mostly immature, only 
a few carrying eggs ; Bosmina ohtusirostris was in extreme abundance. 
The plankton rotifers found were Anuroea cocMearis, Polyarthra platyptera, 
Synchdcta pectinata, and Conochilus volvox. Noteus quadricornis, a rotifer we 
have already found in Scottish lochs, and only in very shallow ones, was 
fairly abundant at the surface over the deepest part. 
“ In March, 1907, the Crustacea were the same, but less abundant, and the 
two rotifers Notliolca longispina and Furcularia reinJiardti were observed for 
the first time. The temperature of the surface was 41°, and at 30 feet 39°‘5. 
“ In contrast to the very rapid stocking of Talla is the case of the new 
reservoir at Holl, in the Lomond Hills, in Fife, where we found none of the 
common lake organisms after the reservoir had been open for a year or 
two. In Logan reservoir, after three or four years of existence, the 
phytoplankton was found very well developed, the diatoms imparting a 
yellowish colour to the water, but the zooplankton was much less abundant. 
These contrasted instances show how little we yet know about the factors 
governing the stocking of a new lake.” 
Loch of the Lowes (see Plate XLIX.). — The Loch of the Lowes 
lies at the head of St. Mary’s Loch, into which it flows by a stream 
about 150 yards in length, the fall between the two lochs being only about 
a foot ; at one time they probably formed a continuous sheet of water. 
The loch is rectangular in outline, and trends almost north and south, 
being nearly a mile in length, and less than a quarter of a mile in 
maximum breadth. The superflcial area is about 99 acres, and the 
drainage area exceeds 10 square miles. The maximum depth of 58 feet 
was observed towards the southern end of the loch. The volume of 
water is estimated at 157 million cubic feet, and the mean depth at 36J 
feet, or nearly two-thirds of the maximum. The basin is simple in con- 
formation, and flat-bottomed in character, as is shown by the fact that, 
while 25 per cent, of the lake-floor is covered by less than 25 feet of water, 
34 per cent, is covered by more than 50 feet of water, although the 
maximum depth is only 58 feet. The loch was surveyed on May 5, 1905, 
