HTDKOZOA. 



249 



first a polyp with pneumatophore and tentacle beneath an apical 

 hydrophy Ilium. The female gonophore has only one egg. 



Fam. Athorybiadae. With a bunch of hydrophyllia in place of the swim- 

 ming column ; resembling a persistent larval stage. Athori/bia rt'sacca Esch., 

 Mediterranean. 



Fam. Physophoridae. s. str. Stem short and enlarged to a spiral sac 

 beneath the swimming column with its double row of 

 nectocalyces. No hydrophyllia but instead two outer 

 bunches of dactylozooids with gonoblastidia, nutritive 

 polyps and tentacles lying beneath them. Pltysojiltom 

 Forsk., Pit. liydrostatica Forsk., Mediterranean (fig. 

 190). 



Fam. Agalmidae. Stem unusually elongated and 

 spirally twisted. Swimming column with two or more 

 rows of nectocalyces. There are both hydrophyllia and 

 tentacles. Fvrsltalia c-ontorta M. Edw., Ilaltstcmma. 

 Dactylozooids and hydrophyllia directly connected with 

 the stem. In the ciliated larva a pneumatophore is 

 first developed at the upper pole. //. rub-rum Vogt, 

 Mediterranean. II. ti'rgc&t'umm Cls. (fig. 1'Jl). Ayal- 

 mvpsis Sars-ii Koll., Ajjali'mia war la Less., Mediter- 

 ranean. Dioecious. 



(2) Sub-order : PJiysalidoe. Stem dilated to 

 form a large chamber, the pneumatophore lying 

 almost horizontally, containing a very large 

 pneumatocyst opening to the exterior. Xecto- 

 calyces and hydrophyllia absent. On the ventral 

 line of the sac are situated large and small 

 nutritive polyps with strong and long tentacles. 

 There are also clusters of gonophores attached 

 to the tentacle-like polyps. The female buds 

 seem to become free-swimming Medusce. 



Fam. Physalidae. With the characteristics of the 

 group Physalia Lam., P. rararcUa Esch. (Aretliusa 

 Til.'), nclttgica, iitriculus Esch., Atlantic Ocean. 



f'/J 



FIG. 102. DijJiyei acu- 

 minata, magnified 

 about 8 times. Sl> t 

 Fluid reservoir in the 

 upper nectocalyx 

 (somatocyst). 



(3) Sub-order : Cali/cophoridce. Stem long and 

 without pneumatophore. Swimming column 

 with double row of nectocalyces (Hippopodidse) 

 or with two large opposed nectocalyces, more 

 rarely with only one nectocalyx. There are no 

 dactylozooids. The appendages arise in groups arranged regularly, 

 and can be retracted into a cavity of the nectocalyx (fig. 192). Each 

 group of individuals consists of a small nutritive polyp, a tentacle 

 with naked kidney-shaped groups of nematocysts, and gonophores. 



