1134 
Proceedings of Royal Society of Edinburgh. [sess. 
is the main form in the plankton samples. On 31st October 
several females have ephippia, yet the greater part have none ; 
the males appear in countless numbers and are now fully developed ; 
even now we find no more young animals. On 16th November the 
Fig. 1. — 14th July, 
young female, 
two eggs. 
Fig. 2.— 31st July, 
female with 
ephippium. 
Fig. 3. — 30th Sep- 
tember, young 
female. 
Fig. 4. — 14th December, 
big female with ephippium. 
Fig. 5. — 14th December, 
small female with ephippium. 
ephippia of most of the females are more or less conspicuous, but 
very few have eggs in them. On 30th November all the females 
have ephippia and in most of them are eggs ; the number of males is 
decreasing. On 14th December only females with ephippia or 
barren females occur; males are wholly wanting. On 23rd 
January the number of D. longispina is but small and consists 
only of females. D. longispina is wanting in all the samples 
