No. 8. — Studies of the Jdly-fishcs of Narragansett Bay. By 

 J. Walter Fewkes. 



TnE following pages contain an account of certain new Acalephce col- 

 lected by me during three summers' work at Newport, K. I.,* with notes, 

 anatomical and embryological, on those which have been previously 

 known. A few jelly-fishes are also described from drawings and notes 

 made by Mr. Alexander Agassiz, since 18G5, at Newport and Naushon. 

 These are mentioned in the appropriate places under the respective 

 meduste. 



HYDROIDA. 



Sarsia mirabilis, Agassiz. 



Flate III. Figs. 11, IS. 



S. mirabilis is rarely found in Narragansett Bay. During the summer 

 months which were spent in Newport, only two specimens of this jelly-fish 

 were found. If one contrasts this rarity of the medusa south of Cape Cod 

 with its abundance at times in the waters of Massachusetts Bay, the conclusion 

 seems evident that the specimens which were captured in the former locality 

 Avere stragglers, and do not strictly belong to the fauna of Narragansett Bav. 

 A portion of the base of the tentacle of S. mirabilis is specialized into a spher- 

 ical body, which projects downwards as the jelly-fish swims in the water, hang- 

 ing below the margin of the bell. 



The walls of this spherical enlargement at the base of the tentacle are formed 

 of two layers, and enclose a number of cellular bodies, which resemble indis- 

 tinctly lasso cells. They appear to have some special function, and are not 

 found in other genera of our coast closely related to Sarsia. Covering the sur- 

 face of the walls in which they are contained, there are many small, bright red 

 pigment dots. The true eye-spot (ocellus) is black, and is mounted on a pa- 

 pilla, which rises on the upper and external side of the base of tlie tentacle. 

 The spherical enlargement previously mentioned is on the under and opjiosite 

 side of the base of the tentacle. A figure to illustrate the general appearance 

 of the tentacular bulb, with the two structures, ocellus and problematical sense 

 organ {spherical body with contained cells), is given, with an enhu-ged view of 

 part of the latter structure, in Plate III. figs. 11, 12. 



• I am indebted to Mr. Agassiz for facilities to carry on this work in his private 

 laboratory, at Newport, R. I. 



VOL. VIII. — NO. 8. 



