CCELENTERATA : HYDROZOA. 



central polypite " (Greene). Velella is about two inches in 

 length by one and a half in height. It is of a beautiful blue 

 colour and semi-transparent, and it floats at the surface of the 

 sea, with its vertical crest exposed to the wind as a sail. 



Fig. -2C).Phyfophorid(e. a Portuguese man-of-war (Physalia utricnlus), showing 

 the fusiform float and the polypites and tentacles (after Huxley) ; b Velella vulgaria 

 (after Gosse). 



DIVISIONS OF THE PHYSOPHORID^E. (AFTER HUXLEY.) 



Fam. \.Apolemiadce. Hydrosoma with nectocalyces and hydrophyllia, 

 the latter united with the other organs into groups which are arranged at 

 considerable intervals along the ccenosarc. Coenosarc filiform. Pneuma- 

 tocyst small. 



Fam. II. Stephanomiadce. Hydrosoma with nectocalyces and hydro- 

 phyllia, the latter arranged with the other organs in a continuous series. 

 Coenosarc filiform. Pneumatocyst small. 



Fam. III. Physophoriadce. Hydrosoma with nectocalyces, but without 

 hydrophyllia. Distal end of the filiform coenosarc dilated. Pneumatocyst 

 small. 



Fam. IV. Athorybida. Hydrosoma without nectocalyces, but with 

 hydrophyllia. Pneumatocyst occupying almost the whole of the globular 



