456 Entomostraca (Water-Fleas). 



duced by using one arm like a leaping-pole against the bottom 

 of the vessel. When full grown, it is mostly covered with 

 diatomaceee and other confervoid growths, so that the conti- 

 nental authors alluded to suppose this to be the reason of its 

 inactivity. Such, however, is not the case, as the following 

 observations will show. A specimen which was sent to me by 

 Mr. Norman to make drawings from, produced, while in my 

 possession, five young ones. These, though they were for a 

 few hours rather more active than their parent, presently 

 took to the same mode of life, and though at first per- 

 fectly free from any parasitic growth, they soon became covered 

 with diatoms, etc. — the result, not the cause, of their inactivity. 



Pertaining to the anatomy and physiology of the Entomos- 

 traca, there is much of the highest interest which we have not 

 at all noticed. 



There is also a large group of parasitic species, deriving 

 their nourishment chiefly from the juices of fishes and the 

 larger Crustacea, concerning which a very few words must for 

 the present suffice. These curious beings infest both marine 

 and freshwater fishes, mostly attacking such as are in a sickly 

 condition — unless, indeed, the sickliness be a consequence of 

 their presence. Fish thus infested are called by the fishermen 

 lousy. Some of these species attach themselves by suckers ; 

 others possess hooks, or anchors, which they bury in the tis- 

 sues of their unfortunate victim, obtaining by this means a 

 hold which baffles every effort at dislodgement. No part of 

 the fish's body is secure from the vermin ; most of the com- 

 moner species live on the skin, fixing themselves in the inter- 

 stices between the scales ; but some forms are found only on 

 the gills and eyes. Fig. 9 is a representation of Lcrnconevia 

 Spratta, a species which has been found attached to the eye of 

 the sprat. Fig. 10 is Nicothoe Astaci, whose habitat is the gills 

 of the common lobster. 



In conclusion, we may say that scarcely any field of re- 

 search offers more abundant chances of success in the disco- 

 very of new species, or more room for investigation towards 

 solving doubtful physiological problems. There are but few 

 labourers in this field, and whilst the student will find in tho 

 monograph of Dr. Baird, published by the Ray Society, and 

 in Mr. White's excellent little Manual of British Crustacea, 

 admirable guides to his researches, he will, in all probability, 

 before he has gone very far, prove for himself, by the discovery 

 of undescribed forms, how little labour has as yet been spent 

 over this interesting group of beings. 



