BY R. VON LENDENFELD, PH.D. 503 



the central cavity. The developemeut of these grooves or canals and 

 of the finger shaped pi'ocesses is different in the different varieties, 

 and hj these external differences the varieties can be readily 

 distinguished. 



In Euspougia canaliculata dura, the digitate processes are 

 most regular, dome-shaped and large, measuring 20 mm., in 

 diameter, whilst the grooves are very narrow and not very 

 numerous. 



The skeleton of this variety consequently possesses a comparatively 

 smooth appearance. 



In Euspongia canaliculata dastica the digitate processes aie 

 longer but more slender, measuring 12 mm,, on an average in 

 diameter and 18 mm., in height. The skeleton of this variety 

 presents a much more irregular aspect because the grooves are so 

 numerous and broad that the sides of the digitate processes appear 

 entirely cut up by them into isolated erect portions. 



In Euspongia canaliculata mollissima the digitate processes are 

 much smaller than in either of the foregoing varieties and not so 

 numerous. They do not take up the whole of the upper surface of 

 the sponge. 



The whole of the surface is covered by a network of meandric 

 grooves, which are of similar dimensions as in Euspongia canaliculata 

 dura. These grooves foi'm anastomoses and in this way cut the 

 whole of the svirface up into numerous irregularly shaped fields. 

 This of course only applies to the skeleton. 



Colour. 

 The colour of the live sponge is brownish grey. It spirits it 

 becomes lighter. Beach worn skeletons of Euspongi% canaliculata 

 dura are of a dirty greyish-yellow colour. Those of the other two 

 varieties are reddish brown the colour of " burnt siena." 



Rigidity. 

 The skeletons of all the three varieties are very elastic, but at 

 the same time much harder than any variety of Euspongia officinalis 

 known to me.- In consequence of this rigidity, Eusj^ongia canali- 

 culata cannot be used for similar purposes as the bathing sponge. 

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