STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 513 



Studies on the Comparative Anatomy of Sponges. 



I. On the Genera Ridleia, n. gen., and 

 Quasillina, Norman. 



By 



Arthur Dendy, M.Sc, F.li.S., 



Demonstrator and Assistant Lecturer in Biology in the University of 

 Melbourne. 



With Plate XLII. 



Some months ago, when going over the large collection of 

 Sponges in the British Museum, I came upon a curious little 

 specimen/ which a cursory examination soon showed to be of 

 exceptional interest. I was therefore led to make a careful 

 investigation of the minute anatomy, and soon discovered that 

 the specimen in question was the type of a new genus of 

 Monaxonid Sponges allied to Quasillina on the one hand, 

 and Suberites on the other. For purposes of comparison, 

 I was further led to make as complete a re-examination as 

 possible of the minute anatomy of Quasillina, which led to 

 an almost complete confirmation of what Dr. Vosmaer has 

 already published on the subject, and also to the discovery of 

 some interesting new points. 



As, therefore, the present paper treats of the anatomy of 

 two distinct though closely allied genera, I have thought it 

 desirable to divide it into two main parts. These two parts 

 are, however, very intimately connected with one another, and 

 perhaps the chief interest of the paper lies in the comparison 



1 Labelled, " H. M. S. * Porcupine,' Station 82," and registered in the 

 collection 83, 12, 13, 69. 



