Sponigia> or Pori/era. 121 



puvm into a oiliatod larva, wliioh atiaolios it^olf after a ■iliort 

 indoiXMnloiit oxisionoo, and i^rows into a now animal. 



The oxtovnal form of tho Spoiii^o (or tlio Spoil go-oolouy) is 

 oxrrenioly A-jvried; it may be massive, more eloii!:;--ate gxi\ilet-sliapod, 

 liisooid, v>r quite irro>riilar. All aiv sos>ilo, ami tho majority ari^ 

 marine ; only a few ooour in frosh wjitor. 



Of nmm^ivns forms only a fow will l>e inetitionod. 



1, Th? Bath Spoil ce (Eu^pottgia), i>f which ihvoi-so sjvoies and 

 varieties are the ol\ieot of important fisheries in the Mediterranejui. possessor an 

 exohis-ivoly horny skeleton, osptvi:illy oh;ii-;u loriso.l In its gix^at ohi:itk-it\ it 

 oan he j>onipletely dried without hivaking. Fresli sjvMig^^* aiv hlaokish in 

 oiihnir. and vvnly when the soft part* are i'emo\-ed do they become lighter. 



•J. Vitreous sponges ( ^frj-.rrfm^HiAr) are silioious forms, characterised 

 by the strikuiir Ivanty of the skeleton, which is like spmi-irlass. A well-known 

 form i\f this givnp is the beantifnl Philipj>ine Venus's Flowei-h:)sket [Eui^lefMla 

 ifpfrgiUHm). -whioh like several of its allies, lives at considerable depths. 



S, Boriiitr Sponges (rnw). small silioious forms, which cs»n oat their 

 \\-:)y into limestone, and lamellihranch vir g;\stro}v->d shells — ilonbtless l\v iuo;)iis 

 of a chemical secretion. In stones or sliells -which they inliahit (they attack not 

 onlv vlejid shells, hut a.lso tlie outer piM-tions of the sliells of living Mollusesl. 

 there is a system of cavities tilled In the body of the SiH->ng»\ and comnmnicating 

 with the exterior hy fine perforations of the snrf;uv of the shell or stone. The 

 Boring Spon^rt^s playan importsuit p;irt in nature, dissolving aw:iy shells and i\"K"ks 

 Abundant in all Euiv}x^:ni seas. 



4 Fresh Water Sponges {SpongiUa _rf«rwWfs, suid other species), 

 abundant in fresh water in England, form colonies of \-;irions foi-ms (hranehing. 

 massive), attached to water plants or jnles. The extermil form of the 

 colony is determined by the snhstiinee npivn which it is givwing. It is a 

 silioions form with simple spionles. In the antnnm i number of gennnuhe 

 arise, rest during tlie winter, and undei-^i furtlier development esirly in the 

 following year. 



