THE PHYSALI^E. 



283 



coloured float, with a crest to it, being partly above water, and a multitude of tentacles, some long 

 and others short, trail behind in the waves. 



The float is sac-like, long, pointed at one end and rounded at the other, and there is a small 

 opening at either end surrounded by muscular fibres. When the float is held in the hand, it feels light, 

 and a little pressure forces air out of it. The sac contains an enlargement of the digestive cavity, 

 and also a long air-sac, divided by muscular partitions, which do not, however, communicate with 

 the digestive cavity, but open 

 externally. Beneath the float 

 are numerous long tentacles 

 without lateral branches, and 

 with kidney-shaped enlarge- 

 ments here and there, armed 

 with nematocysts. Besides 

 these, there are a host of 

 shorter structures, forming, 

 really, a hydroid colony. 

 There are tentaculate in- 

 dividuals, or zooids, called 

 trophosomes, in groups which 

 deal with the nutrition, and 

 bunches of other individuals, 

 or gonophores, with medusa- 

 like buds, and which ai-e repro- 

 ductive. These escape, and the 

 Physalia is their product. 



Physalite are found in 

 vast multitudes, and about 

 1 20 species exist, and they are 

 amongst the most graceful and 

 beautiful objects of the ocean 

 and large seas. 



The sub - order Caly- 

 cophorfe have the hydrosoma, 

 or swimming body, propelled 

 by special swimming bells, or 

 nectocalyces, each of which 

 resembles the bell of a medusa 

 without the root-like processes. 

 The cavity of the bell is mus- 

 cular, and the pedicle of 

 attachment has a process of 

 the body-cavity branching into 

 canals. The bells may be 

 retracted into the mass of the 

 body, which is flexible, un- 



i 1 i /!!/ PHYSALIA UTKICt'LUS. 



branched, filiform, and walled. 



Praya diphyes has two small rounded swimming sacs, nearly alike, and they are placed opposite 

 e end of the body. They have groove-like processes for retraction, and the male and 

 individuals are attached to the same body-mass, or coenosarc. Diphyes is also a genus of the 

 ler, and has two large natatory sacs, one placed, as it were, within the bell of the other. 

 Ihysophora hydrostatica, of the Mediterranean, belongs to another sub-order the Physophor.-e 

 has a rather twisted floating body, whose natatory vesicles are in two rows. Below these is a 

 crown of tentacles surmounting the colony of nutritive, generative, and filamentary zooids. 



