242 DUBLIN UNIVERSITY 



sion, while in captivity ; still, the evidence was not quite satisfactory, 

 and, therefore, it cannot be asserted as a positive fact. Their move- 

 ments, however, are at times very active, and they swim with rapidity 

 up and down in the water, as if in pursuit of some, to our eyes invisible, 

 prey.* 



In this particular there was a striking difference between N. fonta- 

 mis found at Corsham, and its variety at Ring wood ; the latter, in ris- 

 ing to the surface of the water, generally turned the underside of the 

 body uppermost, which the individuals observed at Corsham (which 

 were mostly larger and stronger) did not do. Possibly this may be a 

 habit distinctive of the sexes. 



In moving along the bottom of a vessel, N. fontanm turns its body 

 almost entirely on one side, and in that position, by aid of the hinder 

 legs (using only those at one side of the body at the same time) pro- 

 gresses sideways in a very curious, though not crab-like manner. When 

 resting, it curves itself into the form of the letter c, keeping two or 

 more pairs of the posterior legs extended outwards and upwards, per- 

 haps to balance the body against the effect of currents in the water. 

 At the same time the three anterior pairs of pleopoda, or " swim- 

 ming legs," seem never to cease moving to and fro while the animal is 

 alive. 



Sometimes N. fontanm may be seen to rest itself in an upright posi- 

 tion against the side of the vessel by aid of the extended legs, but more 

 usually I observed it to lie on the bottom, on its side. The last pair of 

 pleopoda seemed to be occasionally used to assist the body in turning 

 round, but not often. 



These remarks have reference only to the one species, as the others 

 were so much smaller in size, and died so much sooner in captivity, 

 that their habits could not be well noted. 



"What is to be said on the localities and habitations applies to all 

 the new species equally. The wells are all artificial, and also those in 

 which they have been found on the Continent ; in England the habitat 

 has in each case been a pump. This is a very remarkable fact, and not 



* Since the above was written, some water, drawn from the pump at Kingwood, lias 

 been proved, by microscopical examination, to contain numerous animalcules; and this will 

 probably turn out to be the case with all other waters in which Niphargi is found. 



