PORIFEHA [sponges]. 



35 



Groups of whip chambers h;ad eacli h\ a short passjige into a coiumon i 

 channel, which joins with other canaliculi to form caiiaLi, tina! 

 opening by the oscules. The whip «haml«.'i-8 form a sort of 

 cordon between the extreme rootlets of th<- in-current and vwt- 

 current canals. 



The horny skeleton, which is imbedded in and which supix)rts 

 the tissues of tiie body, forms a netwurk composcil of radiatiiii.; 

 main fibres connected by a dense meshwork of finer stcondary 

 fibres. 



The Common Bath Sponfre, Ifij>ji(isjHj,(i/ta Kjuina, has a massive 

 cake-shaped body covered with black or dark skin. The body ig 

 permeated by wide channels and cavities separated from eacii other by 



Fig. is. 





J0T<5 





^^^i*\ 





it- 





?s:--r 



?\ 



1-5 

 I. -". 



K;" 



k. 



e' d' ^d r 



A B C 



Toilet Sponge, a. Diagram of Canal System, u. Section allowing <i, pores ; 

 h, canals ; c, whip-chaiubers ; d. skeleton fibres ; d\ main fibre ; e, embryo. 

 C. Whip-chambers. Highly iimgnified. (Afti^r 1\ Iv Sfhiilze.) 



thin walls. The Common Hath Sponge is, in fact, composed of 

 contorted lamellae separated by lal)yrintliine spaces (Fig. lit) ; the 

 large holes on the surface are not oscules, but " i>scudoscnIi-s,'' the 

 true oscules and groups of pores being scattered indiscriminately over 

 the surface of the lamellae or walls of the spaces. Ciu'rents always 

 come out of a true oscule, but they may enter or leave by the h(»les 

 on the surface of, the Common Batli Sponge. See specimens in fluid 

 ill Case I. 



On the floor. of Case I. is a Ijrokeu pitcher with the skeletons of 

 a bath sponge and fine toilet sponge growing on it. ' 



T\iQ S'j)o /Iff ia simofca, or Hard Sponge, which forms a third s|Hri»-s 



1) 1' 



J 



