BY R. VON LENDENFELD, PH.D. 311 



In detail the form of a species is very constant, so that Sponges 

 from the same locality growing in the same depth, and under 

 similar outer circumstances, will always at first sight prove their 

 identity, may their shape differ ever so much. 



The configuration of the surface, the height of the projecting 

 conuli, and their distance from each other, and the size of the Oscula 

 are alike. Also, the structure of the skeleton is much more constant 

 than the shape. 



The more we go into detail the more constant peculiarities are 

 met with, so that the microscopic investigation will often prove 

 two specimens to be identical, which are very different in shape. 



The size is subjected even to greater variations than the form. 

 Many Sponges certainly do not grow beyond a certain limit, bat 

 there are others which grow indefinitely — that is all those forms, 

 which are found in the shape of incrustations. Spongecrusts may 

 extend for miles. The margins of different crusts coalescing, and 

 finally covering the whole of the area in which the Sponge in the 

 struggle for life has the upper hand. 



Such a Sponge is for instance our Aplysilla violacea (1) 

 which covers many thousand square meters in Port Phillip. In 

 such cases it is difficult to say what should be considered as an 

 individual. 



Whilst the Sponges with characteristic shape can be easily 

 recognised either as single persons or as colonies of such, whereby 

 all individuals are alike and moi'e or less separate, these unlimited 

 sponges can only be understood asZoa Impersonalia (Oscar Scmidt.) 

 Together with the characteristic and constant shape we find the 

 individuality of the Sponge slowly disappearing, whereby not cleaiiy 

 personified individuals are derived from personified species of 

 definite shape. This certainly tends to prove that these inde- 

 finite Sponges are not to be confounded with higher indivi- 

 dualized Coelenterata, but we must always bear in mind, that they 

 pass an embryonic stage, which is of characteristic, constant and 



(1) R. von Lendenfeld. Ueber Goelenteraten der Siidsee II. Ntue -Apty- 

 siniJ.a. Zeitschrift fiir wissenschaftliche Zoologic. Band, XXXVIII. 

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