34 ^ 
BATHYMETRICAL SURVEY OF 
common in the September gathering, but was not observed in any of 
the other three. Diapto7nus gracilis was frequent in the gathering 
collected in December, but was scarce in the others. Bythotrephes 
longimanuSy though present in both the September and June gatherings, 
was not observed in those collected in December and March. Cyclops 
stre7iuus, though present in all the gatherings, was scarce. 
A few male Daphiiice were observed in the December gathering, but 
in none of the others ; females with pseudova were frequent in all the 
gatherings. When the loch was examined in June, 1890, both Baplmella 
hr achy ur a and Polyphc7nus pediculus were observed in the tow-net 
gatherings, but neither of these species was obtained in any of the 
gatherings recently collected. Infusoria and micro-algae, which were 
moderately frequent on the first three occasions when the loch was 
examined, were quite abundant in the loch in June, but these minute 
forms did not appear to be generally diffused, apparently occurring in 
shoals, and being particularly plentiful to the south of Reed Bower. 
The examination of the shore yielded a much greater number of 
species than were captured by the tow-nets, but individuals were not 
nearly so numerous. Fifty-five species of Crustacea were obtained in 
the shore gatherings collected during the recent experiments. The 
records of species obtained when the loch was examined in 1890 include 
a few that were not observed in the recent gatherings (viz., Cypria 
exsculpta, Ca7ido7ia lactea, Ilyocypris hiplicata^ Bosmhia longirostris, 
B. lo7igispi7ia), and if these and the species captured with the tow-nets 
be added, they increase the number of crustacean species to sixty-five ; 
it is quite probable that even this number will yet be added to when the 
loch comes to be more thoroughly examined. Only five species were 
observed in all the gatherings in 1890, 1897, and 1898, viz., Gantho- 
camptus staphyliTius , G. TiiBiutus, Gypria oplithahyiica, Ca7idona 
ca7idida, Chydorus sphcericus . The species recently captured include 
one Amphipod {Ga7nr7iarus pulex), and eighteen each of Copepoda, 
Ostracoda, and Cladocera. The largest number of species of Crustacea 
obtained in any of the recent shore gatherings from Loch Leven was 
in that collected on-' 13th June. This gathering yielded thirty-nine 
species, or only four less than the total number observed in the tow-net 
and hand-net gatherings collected in June, 1890. 
The Cladocera, as a whole, were scarcer in those gatherings collected 
in the colder months than in the others. It may also be stated that in 
March the level of the water was much higher than during any of the 
other visits, and this no doubt accounted, partly at least, for the great 
scarcity of Cladocera in the gathering collected at that time ; the 
reduced temperature incidental to the season may also have had some 
influence in bringing about this result. 
Rainfall and Outflow. — An attempt has been made to arrive at an 
