84 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



to judge of their beauty one should see them in the Gulf of Mex- 

 ico, sailing along with their brilliant float fully expanded, their 

 crest raised, and their long tentacles trailing after them. 



Fig. 118. 



Fig. 119. 



Velella. ( Velella mutica Bosc.) 



Another very beautiful floating Hydroid, occasionally caught 

 in our waters, though its home is also far to the south, is the 



Fig. 120. 



Fig. 121. 



Velella (Fig. 120). It is bright blue in color, and in form noi 

 unlike a little flat boat with an upright sail. Its Medusa 

 (Fig. 121) resembles so much that of some of our Tubu- 

 larians, that it has actually been removed on this account from 

 the old group of Siphonophorae, and placed next the Tubula- 

 rians ; another evidence of the close affinity between the former 

 and the Hydroids. 



Fig. 118. 

 Fig. 119. 

 (Agassiz.) 

 Fig. 120. 

 Fig. 121. 



Bunch of Hydras ; a base of attachment, bb b single Hydra, c c tentacles. {Agassiz.) 

 Bunch of Hydrae ; cluster of Medusas ; 6 b Hydrae with tentacles, c d bunches of Medusa 



Velella ; m so-called mouth, a tentacles. (^Agaxsiz.) 



Free Medusa of Velella ; a proboscis, b chymiferous tube, c circular tube. (Jlja-isiz.) 



