34 BATHYMETRICAL SURVEY OF 



common in the September gathering, but was not observed in any of 

 the other three. Diaptomus gracilis was frequent in the gathering 

 collected in December, but was scarce in the others. Bythotrephes 

 longimanus, though present in both the September and June gatherings, 

 was not observed in those collected in December and March. Cyclops 

 strenuus, though present in all the gatherings, was scarce. 



A few male Daphnice 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 Daphnella 

 brachyura and Polyphemus 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 

 ersculpta, Candona lactea, Ilyocypris triplicate, Bosmina longirostris, 

 B. longispina), 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., Caniho- 

 camptus staphylinus , C. minutus, Cypria ophthalmica, Candona 

 Candida, Chydorus sphcericus. The species recently captured include 

 one Amphipod (Gammarus 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 



