HALF AN HOUK WITH SPONGES. 



55 



whole family, as any one who 

 has seen the " Venus's Flower 

 Basket " (Euplectella), or even 

 the " Glass-rope Sponge " 

 (Hyalonema), Fig. 17, will 

 readily admit. The latter 

 sponge, which has for a long 

 time been thought peculiar to 

 the Japanese seas, has recently 

 been dredged up off the coasts 

 of Portugal. The silicated 

 sponges frequently have a con- 

 tinuous siliceous fibre, as in 

 the " roots " of Fig. 17, whose 

 glass-like appearance has 

 given the name to the sponge. 

 The spicules in this species 

 are both very beautiful and 

 various, including a number 

 of shapes and sizes. It will 

 be seen that the " head " of 

 the sponge presents the usual 

 appearance by which we know 

 these particular organisms. 

 The following are three of the 

 most marked of these pretty 

 spicules, Figs. 18, 19, 20. 



The calcareous sponges have 

 their framework composed of 

 carbonate of lime. This group 



Fig. 17. 



Hyalonema mimMis, J nat. size. 



