72 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW, 
Podon polyphemoides and P. intermedius, which are also some- 
times captured in the tow-net with the Hvadne. 
Some beautiful as well as grotesque forms are to be found 
among the Cladocera. What, for example, can be more beautiful 
than the delicate structure of Leptodora seen through its 
perfectly transparent covering, or than Sida crystallina as it 
moves gracefully through the water? or what can be more curious 
than the Bythotrephes with its enormously long postabdominal 
spine, or Leptorhynchus with its long strongly-curved beak, or 
Holopedium with its huge dorsal sack-like appendage? And how 
amusing it is to watch the ungainly movements of J/]yoeryptus as 
it struggles to surmount the difficulties in its way—but the 
pleasures of the study of Natural History are endless. 
The species of Cladocera observed in the Castlemilk material are, 
as previously stated, seven in number, the names of which are— 
Bosmina longirostris (Miiller). 
Ilyocryptus sordidus (Lievin). 
Acroperus harpe, Baird. 
Alona quadrangularis (Miiller). 
Pleuroxus uncinatus, Baird. 
Leydigia quadrangularis (Leydig). 
Chydorus sphericus (Miiller). 
Ilyocryptus has been obtained in several localities in Scotland. 
I have records of its occurrence in Loch Morar, Inverness-shire ; 
in a little loch in the Island of Mull; in Loch Leven, Kinross- 
shire ; and in Lochend Loch, Edinburgh. 
Leydigia appears to be the rarest in Scotland of the seven 
species from Castlemilk. The only other Scotch record I have for 
this species is Lochgelly Loch, Fifeshire. 
Pleuroxus uncinatus is also a somewhat scarce species, though 
it is sometimes moderately common where it does occur. 
Bosmina longirostris, Acroperus harpe, Alona quadrangularis, 
and Chydorus sphericus, are all more or less common throughout 
Scotland. 
While the material from Castlemilk Loch, as collected by Mr. 
Steel, has yielded so large a number of species, it is almost certain 
that if there had been time to have made a more thorough 
examination of the loch the number of species would have been 
considerably increased, 
oo 
