244 



CCELENTERATA. 



recall mouthless polyps and manubria; they are very sensitive and 

 mobile and, while tactile, ajjparently in some cases are digestive 

 organs. Latest to develop in the colony are the sexual bells. 

 They are usually brightly colored and resemble small mouthless 



Fig. \Si.—Stephalia corrmata. (After Haeckel, from Lang.) A, in section; au. canal 

 to float; ka, canal system of stalk; o, mouth ; other letters as in fig. 1.^. 



Anthomedusa? without tentacles. They but rarely (Clirysoriutra) 

 separate from the colony, but usually persist as more or less reduced 

 sporosacs. 



From this it follows that the Siphonophora afford fine examples 

 of division of labor and of the consequent polymorphism of indi- 

 viduals. This can indeed l)e carried so far that many convey the 

 imj)ression of being individuals with a multiplicity of organs. The 

 iSiphonoi)hora are all marine, and occur most abundantly in trojj- 

 ical seas. 



Sub Order I. PIIYSOPIIOPwE (Physonectie). Float present, but 

 small ; next a large .series of swimming bells, and then the other members 

 of the colony. Phijsophora, A<j<ilmia, Wdj/oiuui * (fig. 189). 



Sub Order IT. CALYCOPlioR.E (CulyeouecUr). Float lacking : one 

 or two large swimming bells ; the other individuals in groups which fre- 

 quently separate before becomiug mature, auil wore once regarded, under 

 the name Eudoxia , na. distinct anini;\ls. I'raya, DipJii/es* (fig. 1S9), in 

 warmer seas. 



Sub Order III. CYSTONEC^I.E. Float greatly enlarged ; the cceno- 

 sarcal tube reduced, the individuals (no covering scales nor swimmiug 



