318 HRITISH 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 ont the heart. This 

 latter organ contracts and expands regnlarly, 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, where the external ovaries take their 

 origin. 



In general, it is only the adult female of the Lerneadse 

 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 which 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 

 W'hich 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 



