ATYOIDA POTIMIRIM, A MFD -EATING FRESHWATER PRAWN. 331 
of remarkably long bristles. When tbe band is closed, all 
these bristles meet together to form a long, pointed pencil. 
They are always seen thus in dead animals, and the hands thus 
appear quite unfitted for seizing anything, and give no room 
to suspect what an attractive spectacle they present in the 
living animal, and how beautifully they are adapted to the 
food of the animal. This consists of mud, especially the fine 
mud which settles on aquatic plants and is rich in all sorts of 
minute living creatures, as well as in decomposing animal and 
vegetable matters. When the hand opens, the bristles forming 
the pencil spread out in the same plane, arrange themselves 
almost perpendicularly to the margins of the fingers, and thus 
constitute two broad fans, which can take between them a 
quantity of fine mud particles swept off the leaves of plants ; 
as the hand closes, the bristles also close together again from 
all sides, and thus press together the food collected into a small 
morsel, which is conveyed, or rather flung, into the mouth, all 
the movements being so rapid as scarcely to be followed by the 
eye. Scarcely is one morsel swallowed, when there comes a 
second and then a third hand with a new cargo. When the 
animals are feeding upon the soft mud of the bottom, where 
they have only to lay about them briskly, the four hands whirl 
about one over the other with the most restless rapidity. The 
inner bristles of the fingers are considerably shorter and stifler 
than the outer ones ; the latter are simple, the former pecti- 
nated ; they enable the fingers to strip off: the adherent slime 
from delicate roots and stems, which they take between them. 
It is also very pretty to see the animal lying in wait, if I may 
use the expression, to seize the fine particles of food floating in 
the water, whirled towards it by the outer branches of the 
middle and posterior jaw-feet. The chelae, opened about at a 
right angle, hang down from the fore-arm, and all four of 
them form a transverse series, the second pair of feet, although 
articulated further back, being longer than the first pair ; and 
from the great breadth that each separate hand acquires from 
its long bristles being spread out laterally, they keep watch 
over a very considerable space. From time to time we see one 
or the other of the chelae close up and move towards the 
mouth. 
The structure of the organs of the mouth, like that of the 
hands, is connected with this mode of nutrition, and differs in 
many respects from that occurring in the Palaemonidae and other 
Prawns, as indeed in the other Decapoda generally. The 
hinder maxillae, the anterior jaw-feet, and in a less degree 
also the middle jaw- feet, have a remarkably long, straight 
inner margin, densely clothed with stiff bristles, some of which 
are of very peculiar form. It will be easily understood how 
