PORIFERA [sponges]. 37 



Sponges are sometimes cultivated from euttinp*, care Ixriu*; taken HLh f; 

 that a portion of the skiu is retained iu each piecr. It take« alx)iit J 

 seven years for a cubic inch of sponge to grow to a niarkctahle size. 



Attention is directed to the gigantic Luffaria arrfuri, Xeptunt-V 

 Trumpet (Case II.), from Yucatan, and to the fine fan-hhaiM.-d 

 8])ecimen oi Iaiithella//abelltfonius\tviu-:i{\i it (Ca.se II.) ; the skeleton 

 fibres in these sponges are comparatively thick and core<l with a 

 tliick pith, those of the bath sponges being solid, or with only a 

 slender core of pith. The specimen of J^/ti/lloxpviujiu foHasrens 

 (Case II. 4) shows a curious likeness to a Turbinarian eoml, the 

 oscnles of the sponge resemljliug the calicles of the coral ; but it 

 is uncertain whether these resemblances have any real signitiejiuce. 



Myxospoxgiua or Slime Sponges comprise a small group 

 characterised by the entire absence of a skeleton. Hulisdna forms 

 yellowish-brown slimy crusts on stones. 



[A series of specimens and diagrams illustrating the structure of 

 Sponges is exhibited in an u[)righi table case at the eastern end of 

 the Coral Gallery.] 



