342 THE FRESH-WATER LOCHS OF SCOTLAND 
In Loch Vieragvat, examined 12th May 1904, with a temperature of 
49° *3 Fahr., the old Daphnias were large and stout, with the head 
quite rounded, some of them, however, showing indication that they 
had been galeate ; the young were all quite definitely galeate, but not 
much so. In Loch na Coinnich, examined 7th June 1904, with a 
surface temperature of 68° '0 Fahr., some of the adults were large, the 
spine short and slender, the heads rounded, and they carried about 
seven or eight embryos ; other adults — and these were numerous — had 
just a small galea (see Plate XL fig. 2) and fewer summer eggs ; the 
young were rather more galeate than in the lochs just mentioned. In 
Loch an lasgaich, examined 9th June 1904, surface temperature 66° "0 
Fahr., much the same conditions prevailed, except that Daphnias 
with completely rounded heads were wanting, though the oldest 
specimens had almost lost their galea. In Loch Langavat (Benbecula), 
examined 4th July 1904, with a surface temperature of 58° "0 Fahr., 
the adult Daphnias were mostly non-galeate, and the young ones very 
pronouncedly galeate. It seems very probable, then, that galeation in 
the Daphnias does increase, though not to a great extent, with the 
warming of the waters in summer. 
In one or two lochs the adult Daphnias had a deposit of purple 
pigment on the post-ventral region of the valves, as was also the case 
in a few Lewis lochs ; and I have seen very similar pigmentation in 
autumnal Daphnias from the lakes of Sutherland and Ross-shire. In 
Loch Maol a' Choire (Inver basin), a small lake at a considerable 
elevation, the pigment was deposited in two dorsal areas — one just 
behind the head, and the other posteriorly ; more usually, however, 
such Daphnias have only one pigment spot, situated, as in North LTist, 
post-ventrally. Sven Ekman records the same kind of coloration in 
the D. galeata of Puorek Lake. 
No males or ephippium-bearing females were seen in the North 
Uist and Benbecula lochs during this period. 
In the small, fertile island of Lismore the waters contain an 
abundance of lime salts, and the margins of the lakes have a rich 
molluscan fauna. The lochs (Baile a' Ghobhainn, Fiart, and Kilcheran), 
which are relatively deep, were examined 12th to 16th August 1904, 
when the temperature was high ; Daphnia was apparently absent 
altogether from Loch Fiart, and in the other two lochs it had 
completely rounded head with no trace of galeation either in adults or 
in young forms (see Plate XIII. fig. 3). The head is of characteristic 
shape, the ventral margin being quite straight ; this corresponds fairly 
well with the Daphnia hyalina^ forma typica^ of Ley dig. In Loch 
Baile a' Ghobhainn ephippium-bearing females were found. 
In the island of Mull, two lochs (Ba and Frisa), both rather deep, 
were examined on 16th and 17th August 1904. Daphnia was absent 
