54 Anatomy of Sagartia Schillericma [No. 1, 



We may, therefore, say that the brackish water from Port Canning is 

 composed of very nearly one part of sea, and two parts of river-water. 



The occurrence of a species of Sagartia in brackish water, resembling 

 in nearly all respects of its organisation marine species, is one additional 

 fact how often an animal has it in its power to select or change the con- 

 ditions of its life. It does not apparently depend so much on the quantity 

 of certain solid constituents, composing sea- water, as it does on their 

 presence in general ; smaller quantities of them may occasionally have 

 no effect upon the animal life, but the absence of one or the other 

 of them could likely produce a thorough change in the fauna. 



Considering the great disturbances of the atmosphere which have 

 taken place towards the close of the last year (1867), we could 

 suppose that these corals may have been transferred from the sea coast 

 in the tank accidentally. This however is not the case. Although 

 the water of the river is subject to constant changes of flood and tide, 

 and contains a large proportion of fine mud and silt, which undoubtedly 

 would greatly interfere with the existence of most other corals, the 

 Sagartia live in it in large numbers. I also found them several miles 

 north of Canning, in the tributaries of the Mutlah river, where the 

 water is often much less brackish than further south. Besides the 

 Sagartice there are in the same tanks at Port Canning, and in the 

 neighbourhood, a large number of most interesting species of Mollusca 

 living which mostly belong to marme types. Many of the animals may 

 die or otherwise become less active, when during the monsoons the 

 water of the tanks is nearly quite fresh, but some of them certainly must 

 survive. Pure fresh water, or even that of the Hooghly obtained at the 

 height of the flood, acted injuriously on the Sagartia. The animals, 

 when placed in it were momentarily paralysed, though exhibiting 

 vitality for some time afterwards, but they died in about 24 hours ; still 

 I think it very probable that the specimens would gradually and in 

 time get accustomed to the Hooghly water also and they probably also 

 occur in this river further south, and nearer the sea. 



I have associated with this extremely interesting species, which gave 

 me the opportunity of observing so many new points regarding the 

 anatomy of the Adiniacea, the name of my friend, Ferdinand Schiller, 

 who has been so actively engaged in the improvements of the locality 

 where the species was discovered. 



