24 a 



CCELEXIEBATA. 



Pn 



provisional appendages 

 is formed which allows 

 its to regard the develop- 

 ment of the SipJiono- 

 pliora as a metamorphosis 

 (fig. 188 and 189). 



The crown of hydro- 

 phyllia, which is com- 

 pleted by the addition of 

 fresh hydrophyllia after 

 the appearance of a 

 tentacle with provisional 

 groups of nernatocysts, 

 persists only in Athory- 

 lifi, where a swimming 

 column with nectocalyces 

 is never formed. 



In Af/almopsis and 

 Physophora the primary 

 hydrophyllia of the larva 

 fall off as the stem be- 

 comes larger, and are 

 replaced by nectocalyces. 



(1) Sub-order: Physo- 

 phoridce. Stem short, 

 extended in the form 

 of a sac (fig. 190), or 

 elongated spirally (fig. 

 191), with a pneumato- 

 phore, usually nectocaly- 

 ces, which are arranged 

 in two or more rows on a 

 i-wimming column below 

 the pneumatophore. 

 Hydrophyllia and dacty- 

 lozooids are usually 

 pie.-ent, and alternate 

 with the polyps and 

 gonophores in regular 

 order. The body of the 

 larva usually develops 



FIR. 101. Hinitfemma fcrgfffiinim. Pn, pncumatophnrc 

 S. Nectocalyx ; P, poljp ; D, bydrophy Ilium ; J\"A-, groups of nematocysts. 



