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STUDIES ON THE COMPAEATIVE ANATOMY OE SPONGES. 159 



Studies on the Comparative Anatomy of 

 Sponges. 



V. Observations on the Structure and Classification of the 

 Calcarea Heteroccela. 



By 



Arthur Deiidy, D.Sc, 



Fellow of Queen's College, and Demonstrator and Assistant Lecturer on 

 Biology in the University of Melbourne, 



With Plates 10—14. 



I. Preface. 



The object of the present paper is to give a general account 

 of the anatomy^ histology, and classification of the Calcarea 

 Heteroccela, from the point of view of one who has for some 

 time past been engaged in an independent study of the group. 

 The exceptionally fine collection of Calcarea Heteroccela 

 which I am fortunate enough to have at my disposal must be 

 my justification for making this attempt. 



Concerning the anatomy and histology of the group, I have 

 perhaps not much to say that is new^ but I hope that by 

 bringing together our information on the subject in a collected 

 form I may be of some use to students of spongology. Serious 

 errors have from time to time crept into our information as to 

 the anatomy of the Heteroccela^ and I can only hope that I 

 have not reproduced any of them in this paper. As, however, 

 by far the greater part of my information has been derived 

 from personal observation, I feel tolerably safe in this respect. 



With regard to classification, I have been obliged to depart 



VOL. 35j PART 2. — NEW SEE. N 



