ON THE CANAL SYSTEM OF THE 



HOMOCOELA AND ON THE MORPHOLOGICAL 



VALUE OF THE TERMS OSCULUM AND 



PORE IN SPONGES. 



Dr. G. C. J. VOSMAER 



Lecturer iu Zoology in the üuiversity of Utrecht, Holland. 



The well-kuown spongiologist Dendy ') from Melbourne bas 

 made , as Mr. Bidder ^) says : — the first attempt at an accurate 

 descriptioü of the lower Calcarea since Metschnikoff's paper in 

 1879." Mr. Dendy's paper shows that iu those lower Calcarea, 

 (i. e. Homocoela) there is far more anatomical difference than is 

 generally accepted. His work throws a new light on the anatomy 

 not only of that group but of sponges in general. 



Iu this paper I first iutend to resumé shortly the facts which 

 Dendy bas fouud and theu to compare the canal system of the 

 Homocoela witb that of other sponges. 



I. The canal system of Homocoela. 



It will be necessary to state , in order to avoid coufusiou , that 

 Dendy accepts the general views of Poléjaeif^) as to the divi- 



1) Denot A. A Monograph of the Victorian Sponges. Part 1. The Organisation and 

 Classification of the Calcarea Homocoela. ... Trans. K. Soc. Victoria, iii, 1. 



2) Bidder G. Review of Dendy, A Monograph . ... etc. Qaart. Journ. Microsc. Sc. 

 Vol. xxxii Part. iv. 



3) PoLÉJAEFF N. Report on the Calcarea dredged by H M, «Challenger". In: Re- 

 port Challenger Vol. viii (1884). 



