CRABS AND SHRIMPS 



is freely open to the surrounding water, which enters 

 the slit edge of the shell, behind the tail. Perhaps you 

 wonder why the eggs are not washed out by the respiratory 

 currents; they are in fact maintained in their position only 

 by a slender tongue-like projection from the back of the 

 parent, which appears to have that special object. When, 

 however, the young are ready for freedom, the mother 

 has but to depress her body a little more than ordinary, 

 when the door is opened, and the young easily slip from 

 the receptacle into the open water. 



These tiny odd -looking sprawling things that you see 

 moving about by quick jerks in the same drop of water 

 are the young recently hatched. They are quite unlike 

 their parent, having as yet no bivalve shell, no abdomen, 

 and only three pairs of limbs. The body is a transparent 

 plate, resembling the bowl of a spoon in form, but ending 

 in two points which carry pencils of bristles. The large 

 dark eye is conspicuous in front, and the six jointed and 

 bristled limbs radiate from the centre, projecting stiffly 

 on all sides. The second and third pair are seen to be 

 double, each giving off a branch, which is pencilled with 

 bristles like the principal stem. 



We have not yet done with these tiny Water-fleas. 

 The sediment at the bottom of this jar of water is quite 

 alive with a host of nimble atoms, some of which you 

 may see crawling up the sides of the glass. They are 

 quite distinct from either of the kinds we nave been ex- 

 amining, not only in details of structure, which is more 

 identical indeed than it seems at first sight, but in habit; 

 for whereas they shoot to and fro through the water with 

 great force and rapidity, these can scarcely swim at all; 

 or, if they do, it is with comparative slowness and much 



