240 



MEDUSAE OF THE WORLD. 



differentiated materials, and hence the longer road it must retrace to produce another structure, 

 the hydranth." There are many interesting facts and hypotheses in Morgan's paper which 

 would not be pertinent to this brief discussion. See also, Child, 1907, Archiv. Entwick.-Mech. 

 Organismen, Bdn. 23, 24. Tubularia with its long, sparingly branched stems and isolated, 

 terminal polypites is naturally a more favorable object for such studies than is Obelia, hence 

 the discrepancies in the results attained by Davenport and by Morgan. 



General Characters of the So-called Species of Obelia. 



♦Probably a variety of 0. dichotoma. Description inadequate. 



