No. 5-] VARIATION AMONG HYDROMEDUSAE. 251 



He explains it as probably clue to an enormous expansion of the 

 top of the Ephyra, thus forming the balloon-like body. 



It may not be amiss in this connection to record observa- 

 tions of a similar character as to numerical variations upon 

 the Aurelias of Woods I loll which quite confirm those cited. 



Observations upon the Hydromedusae seem to have been 

 heretofore quite limited. Those of Forbes ('48), Agassiz ('49), 

 Hincks ('68), Romanes ('74-76), Agassiz and Wood worth ('96), 

 include all the more important observations which have come 

 to my knowledge. The latter would seem to be about the 

 only series made upon a large number of specimens with the 

 purpose of ascertaining the extent and character of variation 

 in a single genus. 



SYRACUSE UNIVERSITY, September i, 1900. 



REFERENCES. 



AGASSIZ, A., and WOODWORTH. Bull. J///.c. Comp. Zool. Vol. xxx. 



No. 2. 1896. 



BALLOWITZ. Variation in Aurelia. Arch.f.Entunck.d. Organism en. 1898. 

 BATESON, W. Materials for Study of Variation, p. 424 et seq. 1894. 

 BROWX, E. T. Variation of Tentaculocysts of Aurelia aurita. Qnar. 



Joiirn. Micr. Sci. Vol. xxxviii. 

 BROWX, E. T. Variation of Haliclystus octoradiatus. Ouar. Journ. Micr. 



Sci. Vol. xxxviii. 



BROWN, E. T. Variation of Aurelia. Xatnre. Vol. 1. 1894. 

 FORBES, EDW. British Naked Eye Medusae. London, 184*. 

 HARGITT, C. W. Nat. Hist, of Pennaria. Amer. Xat. May. 1900. 

 HERDMAX, W. H. Pentamerous Aurelia. Xatnre. Vol. 1. 1894. 

 HIXCKS, T. Clavatella. Hydroid Zoophytes, p. 71. 1868. 

 HORXELL, J. Abnormalities in Haliclystus octoradiatus. Xat. Sci. 1893. 

 HORXELL, J. Lucernaria as Degenerate Scyphomedusae. Nat. Sci. 



1893. 



MURBACH, L. Journ. of Morpli. 1895. 

 ROMAXES, J. G. Varieties and Monstrous Forms of Medusae. Journ. 



Linn. Soc. 1874-76. 



SMALL WOOD, M. Morphology of Pennaria. Amer. Xat. 189^. 

 SORBV, H. C. Symmetry of Aurelia aurita. Xatnre. Vol.1. 1894. 

 UNTHAXK, H. W. Pentamerous Aurelia. Xatnre. Vol. 1. 1894. 



