318 
BRITISH ENTOMOSTRACA. 
motion, or an alternate contracting and lengthening itself 
upwards and downwards. 
Nordmann has described what he considers may be 
the liver and brain, and has pointed out the heart. This 
latter organ contracts and expands regularly, but no blood- 
vessels are to be seen, the blood flowing freely about in 
the hollow of the body and arms. The blood is a clear, 
watery-like fluid, composed of three kinds of globules, 
differing in form and dimensions. The internal ovaries 
lie on each side of the intestinal canal, and open by means 
of a canalis deferens on each side of the inferior por- 
tion of the thorax, w T here the external ovaries take their 
origin. 
In general, it is only the adult female of the Lerneadae 
that we are in the habit of observing, and in an animal 
whose organs of motion and perception for the most part 
are merely rudimentary, and whose existence is strictly 
stationary, the manner of life must be very simple. Im- 
moveably fixed upon the fish which serves it for food, its 
existence depending upon the life of its host, it requires 
neither feet to transport it from place to place, nor eyes 
to guide it in its search for fresh abodes. In fact, the 
whole of its active existence consists in the two operations 
of taking food, and propagating its species. We find 
them in all instances more or less deeply fixed in the 
tissue of the parts upon wduch they have taken up their 
habitation, and often so deeply lodged, that little else but 
the oviferous tubes are visible externally. There they 
remain, living at the expense of their host, those that 
inhabit the branchiae or are deeply fixed in the soft tissue 
of the bodies, drinking up the blood; and the others 
which are fixed less deeply, and take up their abode 
under the fins and such places, sucking the slimy juices 
of the skin. As they are never seen to change their place 
of residence, the question naturally occurs — how did 
they come there originally ? Having no feet to propel 
them through the water, and no eyes to guide them, even 
if they possessed the faculty of transporting themselves 
