OUR CARCINOLOGICAL FRIENDS. 95 
A common object—indeed, one of the commonest 
objects of the sands—is the cylindrical mole crab 
or ‘sand-bug’ (Hippa emerita), 
whose vertical burrows open 
up in great number, partic- 
ularly in the lower tidal re- 
gion. The animal is a remark- 
ably rapid burrower, pushing 
itself head downward by means 
of its anterior or thoracic feet. 
As a rule, but little organic 
matter is found within the ali- 
mentary canal of the mole crab, 
which appears to subsist largely 
upon the nutriment extracted from the swallowed 
sand. It constitutes a favorite article of food with 
many fishes. 
HIPPA EMERITA. 
BEACH-FLEAS, HOPPERS, AND SOW-BUGS. 
A walk at almost any hour along the sandy beach 
is sure to stir up a number of the little hopping 
crustacearts to which the name of ‘ beach-flea’ or 
‘sand-flea’ has been applied (Orchestia agilis, Pl. 7, 
Fig. 6). They hop up in front of your footsteps, 
and leave with equal celerity the seat that may have 
been selected for you, but not until you have turned 
over the long line of sea-wrack (dried sea-weed) 
which fronts the ocean at high-water mark can you 
have any just conception of the multitudes that are 
here busily engaged in performing the offices of the 
public scavenger. Decayed and decaying parts of 
both plants and animals are equally acceptable to 
