1904 - 5 .] The Rhizopods and Heliozoa of Loch Ness. 611 
which he believes to be confined to the abyssal region of great 
lakes; into the question of their origin in»Loch Ness he does not 
enter. The problem of the origin of abyssal species is one of 
great interest ; that of their dissemination from lake to lake one of 
great difficulty. 
If it be the case that the fifty Rhizopods peculiar to Swiss lakes 
are all good species, or varieties of some degree of permanence, 
there is nothing surprising in the fact ; it fits in with the other 
biological phenomena. Geneva possesses in the abyssal region 
large numbers of peculiar species, belonging to many diverse 
groups, — Worms, Molluscs, Entomostraca, etc., etc. Everything 
indicates a long-continued isolation, and relatively great antiquity 
of the Lake of Geneva. 
When we turn to Loch Ness we find that the biological 
phenomena are utterly different. The lake is altogether poorer 
in species ; the abyssal region especially is very poor. Hundreds 
of dredgings have been taken by many experienced workers, with 
the most varied apparatus, and the total result (Rhizopods apart) 
is something less than a score of species, every one of which is 
a common littoral form. Everything, in short, indicates that the 
loch, as a biological entity, is of the most recent origin ; there 
has not even been time for it to get very fully stocked with such 
organisms as might easily migrate into it from adjacent countries. 
If, then, there were in Loch Ness Rhizopods peculiar to itself, 
the fact would be an isolated one, without parallel among other 
groups of organisms ; we would be compelled to suppose that 
these animals were capable of more rapid modification than others. 
If, however, we are told that there are in Loch Ness Sarcodina 
peculiar to the abyssal region of the lake, but identical with 
abyssal species of the lake of Geneva, we are confronted with 
a very difficult problem — viz. to account for the transmission 
from one lake to another of heavy animals, living on the 
bottom at depths of hundreds of feet, and which have no 
means of propagation by minute reproductive elements which 
might float to the surface and so subserve the dissemination 
of the species. 
Dr Penard recognises that in Loch Ness there is very little to 
support his theory that there is a peculiar Rhizopod fauna of deep 
