24 BULLETIN OF THE BUREAU OF FISHERIES. 



While by reason of the peculiar interrelations of hydroids and medusa 1 the 

 present paper may here and there touch to a limited extent a phase of the subject 

 included in Nutting's "Hydroids of the Woods Hole region." it will not materially 

 duplicate that work, but rather supplement and extend it, the two parts forming a 

 fairly complete summary of the entire phylum, the Anthozoa alone excepted. The 

 present paper will also include something in the nature of a synopsis of the develop- 

 ment of representative forms, together with data as to habitat, seasonal variations, 

 etc. The region covered will be about that already outlined by Nutting, namely 

 within the limits of a single day's cruise from the Fisheries Station; for example, 

 Cape Cod and Nantucket on the east, the Gulf Stream on the south, and Narragansett 

 Bay or Long Island Sound on the west. 



The or ' r of presentation will follow substantially that adopted by the present 

 writer in tl "'Synopsis of the Hydromedusse," recently published in the American 

 Naturalist, vtfjich follows in general order and nomenclature Haeckel's "System der 

 Medusen," tl. ugh without adherence to that or any special authority, except as 

 noted in the bq&y of the paper. While deploring the more or less chaotic condition 

 of existing systems of taxonomy in relation to coelenterates, it has not seemed 

 expedient to propose any radical changes at present, even if data were available for 

 such an undertaking. A prerequisite thereto, and one open to students of the group 

 everywhere, is the critical study of ontogeny. Unfortunately, this has not only been 

 neglected in too many cases, but the tendency to devote attention to a single phase 

 of the subject, for example, the hydroid, or on the other hand the medusa^ has. 

 perhaps indirectly, cultivated the neglect. It is greatly to be desired that in the 

 future less emphasis be placed upon elaborate monographs of " Gymnoblastic 

 Hydroids" or "System der .Medusen," valuable as these have been, and more upon 

 monographs of I lydromedusse, or, in other words, monographic details of theontogeny 

 of species, constitution of genera, families, ami orders, including also critical data as 

 to the varietal effects of environment, nutrition, etc. Such monographs would afford 

 final data from which a consistent and scientific taxonomy might be established. 



Except in so far as necessary in order to obviate ambiguity, little effort has 

 been devoted in (he present report to details of synonymy, or to the unraveling of 

 conflicting claims of priority, etc. 



GENERAL ACCOUNT. 



Under the general title of "Medusse" are included animals of a remarkable 

 ranee of size, habits, distribution, and life history. In size they vary from less I ban 

 a millimeter in diameter in the adult condition, as in many of the Hydromedusse, up 

 to enormous specimens of Scyphomedusse, more than '2 meters in diameter and with 

 tentacles more than 30 meters in length. 



One of the interesting anomalies associated with some of these animals is that 

 notwithstanding their large size, no less than '.)'.» per cent of the entire mass is com- 

 posed of water, so that a specimen exposed upon a clean surface to the desiccating 

 influence of sun and air would, after a few hours, leave hardly sufficient organic 

 matter to identity the place. Such being the case it might not be a wholly unwar- 

 ranted paradox to define .a medusa as organized and animated sea water. 



In habit most medusa' are marine, though a few are known to occur in fresh 



