102 THE ROYAL NATURAL HISTORY. 



infusion ' is then transferred to a larger bottle, which is emptied 

 into the aquarium with as little delay as possible. By this means 

 food is supplied to the inmates, and numerous curious additions 

 obtained to the permanent stock. The Hydras are very attractive 

 creatures, of which two kinds may be expected in most localities, 

 H. fusca of a dull greyish or pinkish tinge, and H, viridis. a bright 

 green ; the latter is interesting, being an animal which owes its 

 colours to chlorophyll. 



Among the creatures to be excluded we must name the com- 

 mon water wood-louse, Asellus aquaficus, and the fresh water 

 shrimp, Gammarus pulex^ which, although said to be carnivorous 

 in their habits, we find to be very destructive to plants, biting 

 through the growing stems and thus cutting them adrift. 



With regard to apparatus for collecting, the only indispensable 

 article is a good pair of eyes. A vasculum holding a few quinine 

 vials, and a small muslin net, which can be tied to the end of a 

 walking-stick, is all that is needed ; the net may be supplemented 

 with a bottle similarly attached, for the smaller forms of life, 

 which may be picked out from the dippings by a glass tube used 

 as a pipette. These may be usefully supplemented by the filter- 

 ing arrangement which we have described above." 



"^be IRopl matuial "Ibistor?." 



^ 



W'" E have to congratulate both the editor and the publishers 

 on the completion of the second volume of this fine work. 

 The volume in front of us concludes the account of the 

 Carnivora, and includes the whole of the order of Ungulates, 

 finishing with the order Sirenia. 



Where all is so good, it is difiicult to quote any especial part 

 without citing so much that the publishers would be down upon 

 us for pirating. But we cannot resist giving the following anecdote 

 relating to " the lasting and pernicious effects of even a drop of 

 skunk secretion." The story is told by Mr. W. H. Hudson about 



* Edited by Richard Lydekker, B.A., F.R.S. (London: F. Warne and 

 Co. Published monthly. Price i/-) Vol. IL (Parts 7—12), 1894. 



