904 THE HOMOCCELA DESCRIBED FROM AUSTRALIA. 



thick in the middle than at either end, and which therefore 

 appear spindle-shaped. These attain a height of 4 and a thick- 

 ness of 1-5 mm., and [)Ossess two frills of acorate spicules I'ound the 

 month. 



Yiewed with the magnifying glass the outer surface presents a 

 hairy appearance, and the Oscular frill is found to consist of two 

 sets of spicules, one set longitudinal, parallel to the axis and the 

 other set divergent. 



The hairy appearance is caused by acerate spicules, which are 

 situated in tufts, one tuft at the end of each of the numerous 

 protruberances, which give the whole a papillate appearance. 



These spicules are turned towards the Osculum, they are longest 

 in the central pare and shorter towards the narrow ends. The 

 surface of the Spongorhiza, as I propose to call the creeping stems 

 is covered with vertically projecting spicules, shorter than the 

 others. 



Structure : In the central part of the Sponge, where it is 

 thickest, we find that tubes extend from the central Gastral cavity 

 radially, perfectly similar to the ciliated chambers of the Syconidaj 

 On the dermal surface each I'adial tube is found to project a good 

 distance. In the vaulted ends of these chambers, as well as in the 

 body wall, where no chambers are developed, numerous pores can 

 be detected. 



One might from this be led to suppose that my Homoderma 

 Sycandra is only a young Sycon. 



I must state that I have examined a great many specimens of 

 this Sponge, and that I never found any larger individuals than 

 those of 4 mm., and that evidently this was the limit of growth, 

 because the central ones of large colonies were all of this size 

 throughout. I have repeatedly detected mature sexual products 

 in these Sponges. 



The Oscular tube is very wide, of the same diameter as the 

 Gastral cavity ; the walls of it are very thin, and the sarcode 

 extends in good Osmic acid specimens far up the spicules of the two 

 frills. 



