88 
BRITISH ENTOMOSTRAOA. 
instituted a series of experiments upon this subject, with 
regard to the Daphniae, and his results are, that after 
having exposed the insect with eggs in the matrix for a 
considerable time to a dry atmosphere, and then replacing 
it in water, the eggs did not lose their vitality, but were 
after a time hatched as usual. Sulzer, as quoted by 
Straus, says the parents return to life also ; but in the 
experiments reported by Straus, he never found either the 
mother or the eggs recover their vitality. The food of 
these animals, according to Straus, consists of vegetable 
matter, and not animal ; but I have no doubt that they 
are carnivorous, as I have invariably found, that of two 
groups placed in separate vessels of clear water, the one 
having only particles of vegetable matter placed beside 
them, while with the other there were also introduced in- 
fusorial animalcules, the latter were much stronger and 
more active, and throve better than the former. (Vide 
supra, p. 6.) 
I have divided the animals belonging to the family 
Daphniadae into two sub-families, according to the number 
of their feet and the construction of their large antennae 
or rami. 
DAPHN1NA. 
Five pairs of feet. Inferior antennae, two-branched ; 
one branch divided into four, the other into three articu- 
lations. 
1. Daphnia. — Head produced downwards into a more 
or less prominent beak. Superior antennae exceedingly 
small, one-jointed, and situated under the beak. 
2. Moina. — Head rounded and obtuse. Superior 
antennae of considerable length, one-jointed, arising from 
the front of the head, near the centre. 
3. Macrothrix. — Head terminating anteriorly in a 
sharp beak, directed straight forwards. Superior an- 
tennae of considerable size, one-jointed, and hanging 
pendulous from the beak. 
