The Zoologist— July, 1869. 1765 



Scandiuavian naturalist) its near relative, the hag (Myxine glulinosa), is tilled directly 

 liy fresh water. Plaice, flounders, and soles, all three of them marine fishes, are 

 known to live permanently and to attain excellent condition in fresh water. The 

 prawn {Palamon), a well-known marine crustacean, has been repeatedly brought to me 

 by hundreds and thousands, alive and well, in perfectly fresh water, and T have trans, 

 ferred them to their natural sea water in aquaria without any gradual preparation, and 

 without doing them any harm. I have known the common shore crab (Carcinus) and 

 the American horseshoe crab {Limalus), both marine, to run about a garden for days, 

 moistened only by rain. Oysters may be seen daily in shops in London, alive and 

 well, immersed in fresh water. Indeed, it is evident that a large number of marine 

 animals and plants living between tide^marks, must be capable of enduring unharmed 

 the heavy rain which frequently falls upon them uninterruptedly during the recess of 

 the tide; and among such creatures, and so rained upon, few are mure common than 

 the sessile barnacle which infests ships' bottoms. I have found a marine alga (Ulva) 

 growing in the River Thames at Greenwich, where the water is practically fresh, and 

 yel another marine alga (Gn^^Asia) is instantly killed by being plunged in fresh 

 water, its colour being at the same time discharged. Mv. L. Lloyd mentions three 

 marine fi»h which in Sweden and Norway are also found in fresh water, namely, the 

 cod, the whiting, and one species of Coitus. But, on the other hand, there certainly 

 is a large number of marine animals which fresh water, or even weak sea water, does 

 kill almost immediately, as Dr. Wailich says. For example there is a well-known 

 passage in the late Professor Edward Forbes's " History of British Star-fishes," in 

 which he relates how certain marine animals he was dredging for were paralysed in 

 being drawn through a thin layer of surface fresh water floating on the sea-water 

 below. Bui, among the marine animals on which fresh water is supposed to act as a 

 certain poison, none have been so constantly quoted as sea anemones. The late 

 Dr. George Johnston, in his ' History of British Zoophytes,' 2nd edit. 1847, p. 239, 

 says, " These creatures, almost indestructible from mutilation and injury, may be 

 killed in a few short minutes by immersion in fresh water." This work was the ac- 

 cepted authority on these animals for some years before the introduction of aquaria, 

 but it is now almost useless, as far as sea anemones are concerned, and this almost 

 universally accepted statement of Johnston's is certainly incorrect, for I have known 

 specimens of Aclinea Mesembryanthemum thrown away by mistake as dead, and 

 afterwards be found brilliantly expanded in a jiuddle of rain-water in a Loudon 

 garden. Mr. Gosse has lately recorded a sea anemone living in India, in one of the 

 mouths of the Ganges, where the saliness of the water is only about len pans in a 

 thousand, instead of thirtyfive ])urts, as on the coast of Britain. These animals are 

 also found in the Baltic Sea, where the density is only about fifteen in a thousand. 

 The Fauna of the Baltic is a singularly mixed one. Thus among a large number of 

 truly marine animals (some in no way differing in siee from those in the neighbouring 

 North Sea, but others much dwarfed), may be seen swimming the common fresh-water 

 perch, and two species of the common fresh-water stickleback, and of these two, the 

 perch will live if transferred to quite fresh water, and will die if put into quite sea 

 waters while the two sticklebacks will live quite well if removed from ihe Baltic water 

 and be placed in either fresh water or fully dense North Sea water. But there is a 

 deep purple variety of the common North Sea star-fish (Urasler Tubuns) living in the 

 Baltic which is killed directly on being placed in North Sea water; and by uo gradual 



