332 
BATHYMETRICAL SURVEY OF 
elegans, Micr aster ias furcata^ Staurastrum furcigerum^ Xanthidium 
suhhastiferum. 
Loch an Dithreibh. — Bosmina ohtusirostris, var. longispinay Flos- 
cularia pelagica, Staurastrum ophiura^ cysts of Geratium. Animal 
life (both as to individuals and species) was very scarce, while the 
smaller algae were conspicuous. 
Loch na Meide. — Diaptomus laticejjs, D. laciniatuSy Cyclops gigaSy 
Daphnia (galeate), Ilyocryptus acutifrons, Gastropus stylifer = Notops 
pygmceus)y Staurastru^n ophiuray S. arctiscoUy S. pseudopelagicuniy 
Micr aster ias apiculatay var. fimhriata. This loch was remarkable for 
the abundance of both animal and plant life; about eighty species of 
organisms were found in the first cursory examination. The true 
plankton was not, however, particularly rich, there being a very large 
admixture of littoral species. Ilyocryptus acutifrons was first observed 
in Scotland in this loch, though it was afterwards found that it had been 
collected in Loch Shin at an earlier date. 
Loch N aver . — Diaptomus laticepSy Bosmina ohtusirostris (small, with 
long spine), Floscularia pelagicay Gastropus stylifer y Staurastrum 
ophiuray S. arctiscon, S. grande , Micr aster ias confertay M. furcata 
(typical, also a variety having the whole surface covered with hemis- 
pherical papillae of unequal sizes). 
Loch Chaluim. — Daphnia (two forms, first with small rounded head, 
second with very large broad, depressed head, many males), Synchceta 
pectinatUy Gastropus stylifer , Polychcetus collinsiy Staurastrum ophiuray 
S. arctiscon y S. f urcigerum. 
Loch Laoghal. — Bosmina ohtusirostris , var. longispinay Floscularia 
pelagicay Triarthra longiseta, Clathrulina elegans y Staurastrum pseudo- 
pelagicuiiiy S. jaculiferum. 
Loch Creagach is connected with Loch Laoghal by a wide channel, 
and stands at the same level. The biology calls for no separate mention. 
Note on Clathrulina elegans , Cienk. — Skeletons of this animal were 
abundant in the deep lochs Hope and Laoghal. In an earlier paper* 
an attempt was made to account for the presence of these empty shells 
in so many of the Scottish lochs, and as a general rule only in large 
ones, on the supposition that they were derived from the shallow waters 
in which G . elegans is known to live, attached to water-plants by a 
slender stalk. Up till quite recently only empty cases had been found, 
or at most an occasional shell containing an encysted mass of protoplasm, 
and on these facts was based the suggestion put forward as to their 
origin. A fresh aspect is put upon the inquiry by the recent observation 
that in Loch Lochy, where the animal was abundant in August, 1905, 
when the loch was visited in company of Prof. Bachmann, most of the 
shells contained living animals, whick extended their pseudopodia and 
See p. 291. 
