ON THE FOOD OF UTRICULARIA I'ULGARIS 109 



20 contained six organisms each (equal to 120 specimens). Of 



these 24 were Cyclops (all $ ) ; 3 Canthocamptus; 91 Cypris ; 

 i small Annelide ; and i insect larvse. 



30 contained seven organisms each (equal to 210 specimens). Of 

 these 56 were Cyclops (all $ ) ; 3 Canthocamptus; and 151 

 Cypris. 



23 contained eight organisms each (equal to 184 specimens). Of 

 these 27 were Cyclops (246% i?, 2?); 5 Canthocamptus ; and 

 152 Cypris. 



21 contained nine organisms each (equal to 189 specimens). Of 



these 33 were Cyclops (31^, i ? , i ?) ; 4 Canthocamptus; 

 151 Cypris ; and i small Annelide. 



12 contained ten organisms each (equal to 120 specimens). Of 

 these 32 were Cyclops (all $ ) ; 4 Canthocamptus; and 84 

 Cypris. 



12 contained eleven organisms each (equal to 132 specimens. Of 

 these 43 were Cyclops (all $ ) ; 2 Canthocamptus; and 87 



10 contained twelve organisms each (equal to 120 specimens). Of 

 these 23 were Cyclops (21 , 2 ? ), and 97 Cypris. 



4 contained thirteen organisms each (equal to 52 specimens). Of 



these 12 were Cyclops (all c? ) ; 2 Canthocamptus; and 28 



The total number of organisms in this second lot of 

 utricles was 1523, and comprised 362 Cyclops (343 $, 12$, 

 7 ?) ; 40 Cantlwcamptus ; 1113 Cypris ; 2 " Water-mites " ; 

 3 small A nnelides ; and 3 insect larvae. 



Dividing 1523 (the number of organisms) by 289 (the 

 number of utricles containing matter that could be identified), 

 we get an average of about 5^- specimens to each utricle, or 

 more correctly 5 '2 69 8 specimens. The average number of 

 specimens to each utricle in the two lots is thus remarkably 

 close, and on that account is worthy of note. But though in 

 this instance the averages are practically the same, it is highly 

 probable that they would have varied more or less if the two 

 lots had been from widely different localities. 



Having ascertained so much concerning Utriadaria 

 vulgaris from Gullane ponds, I next endeavoured to find out 

 approximately the average number of utricles on a piece of 

 stem of a given length ; and for this purpose I carefully 



