124 



COSLENTEEATA 



and driving out the air or gas through a pore in its upper side. In 

 order to rise to the surface again it fills the pneumatophore with a self- 

 generated gas. The suborder contains 30 species grouped in 5 families. 



FAMILY PHYSALIIDAE. 



With the above-described characters : 4 genera and 10 species. 



PHYSALIA Lamarck. Pneumatophore 

 with a dorsal crest with transverse septa: 

 4 species. 



P. pelagica Bosc. Portuguese man-of- 

 war (Fig. 207). Pneumatophore up to 12 

 cm. long, pear-shaped with iridescent col- 

 ors; tentacles long, sometimes stretching 

 10 or 15 meters, and with powerful stinging 

 organs: in the Gulf Stream from Florida 

 to Vineyard Sound and occasionally to the 

 Bay of Fundy; often common. 



SUBORDER 3. PHYSONECTAE. 



Fig. 207 



PhysaUa pelagica 

 (Lankester). 



Siphonophores with a pneumatophore 

 with a long trunk or axis from which bud 

 off nectophores and successive similar 



groups of individuals, each group containing usually a bract, a gastro- 

 zooid, a palp, a tentacle, and a gonozooid: 9 families and about 75 

 species. 



FAMILY AGALMIDAE. 



Two longitudinal rows of alternating nectophores; trunk long, bear- 

 ing numerous groups of individuals: 30 species. 



CTTPULITA Quoy and Gaimard (Nanomia A. Agassiz). Four to 6 

 nectophores in each row; individual groups not all of the same impor- 

 tance, there being secondary groups lacking the gastrozooids between 

 the principal groups: several species. 



C. cara (A. Ag.). Length of colony about 11 cm.: Newport and 

 Massachusetts Bay. 



SUBORDER 4. CALYCONECTAE. 



Siphonophores with very large swimming individuals (nectophores) 

 and without pneumatophore or palps, the individual groups consisting 

 each of a nutritive and one or more reproductive individuals, a covering 

 bract, and a short tentacle. The colony swims rapidly, in contrast to 

 most Siphonophores, being partly sustained by a drop of colored oil 

 present in each nectophore: 5 families and 95 species. 



