74 



IXVEETEBliATE ANIMALS. 



of the CahjcoplioriiJif: are iu the fmiu of niedusiform goiioi)hores, 

 which are budded from the stalks of the polypites, and which are 

 mostly detached to lead an iiidejiendent existence. 



The second older of the (Jceanic Hydrozo.a is that of the Pltyso- 

 phoridce {(iv. ji/'i/sn, a l>la(lder ; and jJiriri, I carry), of which the 

 most familiar, though not tlie most tyjiical, example is the Portu- 

 guese Man-of-war, Pliisalin (tig. 4;"), u). The I'hijxoplioridie are 

 distinguished from the organisms which we liave been just con.sider- 

 ing by the fact that the proximal e.xtremit}' of the coeuosarc is devel- 



Fi;,'. 40.— f' Piii-tn^ni'se Man-of-war (Pliy^aJii 

 h \\-hll,j, r,il:niris. 



oped into a structnn! wliirli is known .as the " tloat " or "))neumato- 

 pliore." Tlie tloat contains a larger or smaller ,sac, composed of 

 .some elastic lioi'ny sulist.aiicc, jirobalily cliitiiu!, often connnnnic.atiiig 

 with the exterior liy one or more apertures, ;ind always more or less 

 completely tilled with air. The functifin of the float is no doidit 

 that of enabling the org.iiiisni Id maintain its ]iosition at the surface 

 of tlie si'.a, A.s in the (':i/i/coji/inn':/iv, the coaiosarc is ahv.ays jierfectly 

 ilexilili., rcjiiliMi'tile, .and soft, and is never fnrinshed with any 



