216 VELELLID^. 



Family VELELLIDiE Esch. 



Velellidce Esch. {restr. Agass.). Syst. d. Acal., p. 165. 1829. 



Velellce Less. Zooph. Acal., p. 560. 1843. 



Velellidce Agass. Cont. Nat. Hist. U. S., IV. p. 366. 1862. 



VELELLA Lamk. 



VelellaLAMK. Anim. s. Vert., 11. 1819. 



Velella Lkss. Zooph. Acal., p. 562. 1843. 



Velella Agass. Cont. Nat. Hist. U. S., IV. p. 366. 1862. 



Rataria Esch. Syst der Acal., p. 166. 1829. 



Chrysomiira GeGenb. ; in Zeit. f. Wiss. Zool., p. 231. 1856. Medusa. 



Linuche Esch. Syst. der Acal., p. 91. 1829. Medusa. 



? Rataria Pagenst. ; in Zeit. f. Wiss. Zool., XH. p. 496. 1863. 



Velella mutica Bosc. 



Velella mutica Bosc. Hist. Nat. d. Vers, II. p. 158. 



Velella mutica Less. Voyage de la Coquille, PI. 6. 1829. 



Velella mutica Less. Zooph. Acal., p. 571. 1843. 



Velella mutica Agass. Cont. Nat. Hist. U. S., IV. p. 366. 1862. 



The free Medusa of Velella resembles so exactly that produced by 

 some of the Tubularians — Euphysa and Globiceps, for example — that 

 it would seem the most natural thmg to place these Medusaa among 

 Tubularians, as McCrady has done ; but the polymorphism of the 



Hydras (Fig. 355) and the presence of the float (Fig. 356) associate 

 the Hydrarium with the Porpitse. The free Medusa is but another 

 link showing how close is the relation between the floating and fixed 

 Hydroids. The Medusa figured here (Fig. 357) is one which has just 

 freed itself The chymiferous tubes, as well as the proboscis, are of a 



Fig. 355. An enlarged view of one of the fertile Hydrse of Velella. a, base of attachment of 

 Hydra ; 6, end of Hydra ; d, d, clusters of Medusae. All these figures are copied from Professor 

 Agassiz's Contributions, Vol. IH. 



Fig. 356. Velella, seen from below, to show the Hydrae. m, opening, so-called mouth ; a, fer- 

 tile Hydrae situated between the mouth and the outer tentacles, the sterile Hydrae. 



Fig. 357. Magnified view of a free Medusa of Velella mutica Bosc. o, proboscis ; 6, chjinif- 

 erous tube ; c, circular tube. 



