THE ROTIFERA OF THE SCOTTISH LOCHS. 158 
When we scrutinise the three lists carefully, however, and observe how greatly they 
differ in detail, how much richer the American list is in Rhizota (though admittedly 
deficient in that order) than either of the others, how much more numerous are the 
Bdelloida in the Scotch list, and how very few the Rhizota, it becomes evident that the 
coincidence in numbers is purely fortuitous. The Rhizota are not deficient in the 
Scottish lochs—they are particularly abundant, as Mr Hoop’s records show ;* there is 
no reason to suppose that Bdelloids are scarce in the Great Lakes or in Finland—only 
that they have been less studied. 
Confining the comparison of Srenroos’s list to those compiled for the single lake 
most thoroughly examined by JeNNiNGs and by the Lake Survey, we see that the 
Finnish list is the most extensive. SreNRoos got 157 species in Nurmijirvi-See, 
JENNINGS 132 in Lake Erie, the Lake Survey 148 in Loch Ness. 
Loch Morar was visited several times, and 54 species were identified ; 30 were noted 
in Loch Karn, 34 im Loch Tay. These numbers are merely an index to the time spent 
in the examination of the lochs, not to the number of species in them. There is no 
reason to doubt that the Rotifer-fauna of all our deep lakes is in the main identical ; that 
of the shallow lakes on the whole richer, and locally more varied. 
The classification of the Rotifera is in a chaotic state. Since the completion of 
Hopson and Gossr’s monograph (22) in 1889, the number of known species has been 
doubled, and many of the new forms do not fit into the old divisions. New genera and 
families have been formed, and the old families redefined, to admit them; but a new 
monograph is now a desideratum, to bring all the diverse forms into one comprehensive 
view, and allot them their natural places. Most of the genera are in urgent need of 
revision. Excellent revisions of single groups have already been made by RovssEixr, 
of Syncheta (46); Dixon-Nourraty and Freeman, of Diaschiza (12); by Jennines, of 
the Rattulidee (27); etc. Similar studies of most of the large genera would be a useful 
preliminary to the preparation of a monograph. 
Most authors still continue to recognise, sometimes under protest, the unnatural 
suborders Loricata and [lloricata, though it would generally be admitted that the 
possession or lack of a lorica is properly only a specific, or at most a generic or family 
character. Hupson and Gossr’s classification is here followed, with such additions as 
new discoveries require, and in the Bdelloida a radical redefinition of most of the 
genera, which, however, can only serve a temporary purpose. 
In studying such an extensive group as the Rotifers, few can have the comprehensive 
knowledge possessed by Rousseter. Most workers will find it desirable to limit them- 
selves to a special study of some smaller group. To such necessary limitation we may 
ascribe some of the deficiencies of this list. These have been to some extent made 
good by sending collections and sketches to specialists. 
In the preparation of the list I have been greatly assisted by Messrs Bryce and 
* About half the known species of Plosewlaria were first discovered by Mr Hood in Scottish lochs, and of this genus 
alone he has found more species in the lochs than there are Rhizota in this list. 
