﻿ELLIOTT SOCIETY. 



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ach to the marginal bulbs. Nemopsis thus passes through a form 

 like that of Hippocrene, and must therefore be ranked above it. 



I give the above details partly to show how important it is in 

 describing Medusas, to ascertain as far as possible all their changes 

 during growth. Ff. 1 and 3, might very well be mistaken for 

 distinct species. 



The hydra of this species is extremely like Acaulis described 

 by William Stimpson, in his Marine Fauna of Grand Manan. I 

 have only observed the development in one specimen. It was float- 

 ing at large, and taken with the dip-net. It lived five days, devel- 

 oping medusas, but never fixed itself; only gradually dwindling 

 away as the medusse were developed. The tentacula were all, 

 at last, retracted, especially those around the broad base. In its 

 first activity it was incessantly moving about by means of its ten- 

 tacula, mouth downwards. 



I surmise that Acaulis belongs to this group of Medusas. To- 

 gether with this larva of Nemopsis, it should be compared with 

 the young stage of Tubularia when first freed from the bell of the 

 medusa. 



Nemopsis Gibbesii is a winter species. I have found large 

 specimens as early as the 10th December. It may be taken also 

 as late as the 10th of June. It is frequent during May. I have 

 found it in the latter part of April, and the larva and young just 

 described were taken on the last day of January. I have never 

 found a naked-e} T ed medusa in Charleston harbor during the early 

 part of January. 



HIPPOCRENE. Agass. (1849.) Mertens and Brandt (pars.) (1835.) 



General form spherical. Sexual organs in four lobes round the 

 digestive trunk, to which they are confined. Oral tentacula 

 smaller and less ramified than in Nemopsis. Radiate tubes four. 

 Compound marginal bulbs four also, bearing a variable number of 

 similar, simple, solid, and extremely contractile tentacula, which 

 bear their ocelli on the inner or under side, in this respect it differs 

 from Bougainvillia, whose ocelli seem to be on the upper side of 

 the tentaculum. Larva is a small Eudendrium-like hydroid polyp 

 with a branching stem, whose twigs are each terminated by a 

 conical mouth, surrounded by a single whorl of few tentacula. 

 The body of the polyp is of the same width as the stem, and is 

 not distinguished from it by a constriction, the stern itself appa- 



