HTDfiOZOA. SIPHOXOPIIOBA. 



249 



first a polyp with pneumatophore and tentacle beneath aD apical 

 hydrophyllium. 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. Athorybia rosacca 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. Pltysopliora 

 Forsk., Ph. 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. Forsltalia oontorta M. Edw., Halistemma. 

 Dactylozooids and hydrophyllia directly connected with 

 the stem. In the ciliated larva a pneumatophore is 

 first developed at the upper pole. H. rubriim Yogt, 

 Mediterranean. II. tergestinum Cls. (fig. 191). Agal- 

 mopsis Sarsii Koll., Apolemia uvaria Less., Mediter- 

 ranean. Dioecious. 



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

 form a large chamber, the pneumatophore lying 

 almost horizontally, containing a very large 

 pneurnatocyst opening to the exterior. Necto- 

 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 Pliysalia Lam., P. carat ell a Esch. (Arethusa 

 Til.'), yelagica, utriculus Esch., Atlantic Ocean. 



(3) Sub-order : Calycoplwridce. Stem long and 

 without pneumatophore. Swimming column 

 with double row of nectocalyces (Hippopodidae) 

 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. 



FIG. 192. Diphyes acu- 

 minata, magnified 



about 8 times. Sb f 

 Fluid reservoir in the 

 upper nectocalyx 

 (somatocyst). 



