BY R. VON LENDENFELD, PH.D. 487 



ElGIDITY. 



The skeletons are elastic and not very hard. Small specimens, 

 measuring about 50 mm. across are compressed by the weight of 

 1 kilogramm, about 15 mm. on an avei-age. 



Some specimens of Euspongia irregularis tenuis are much softer, 

 and one measuring 4:0 mm. was compressed 50%, that is 20 mm., 

 by the same weight. 



This sub-variety might be used for bathing purposes but seems 

 to be rare. I have only seen one single specimen which came 

 from Mauritius. 



Eusjjongia irregularis Jacksonia is the hardest of all. . 



Colour. 



Only the varieties Euspongia irregularis silicata and Jacksonia 

 have been seen by me in the live state ; their colour is light 

 brownish yellow, but varies apparently according to the size or 

 age of the sponges. The largest specimens are very dark in 

 colour, while the small ones are of a light Melange. 



In spirits the colour is fairly well preserved but becomes duller 

 and lighter. 



Beach-worn skeletons differ very much in colour. Those of 

 Euspongia irregularis silicata are dark dirty greyish brown. Those 

 of Euspongia irregularis lutea are of a remarkable orange-brown 

 colour, similar to burnt "siena." The skeletons ot Euspongia 

 irregularis tenuis are very light in colour. 



The very soft specimen from Mauritius referred to above is of a 

 pretty light brown colour. Others are nearly white, or very light 

 grey. 



The skeleton of Euspongia irregtdaris Jacksonia is dark chest- 

 nivt.^brown. It is, according to this possible, to distinguish the 

 varieties of this species from one another by the colour of their 

 beach-worn skeletons. 

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