136 Papers from the Marine Biological Laboratory at Tortugas. 



have come under the observation of the writer, as in the case of the species 

 mentioned above. In his attempt to gather data for this study the writer 

 has been most generously aided by the Carnegie Institution of Washington, 

 a debt which he acknowledges with gratitude. An appointment as research 

 assistant in 1903 made it possible to collect and study the Medusas of various 

 points on the coast of New England, the somewhat voluminous notes upon 

 which have not yet been published because so few of the many questions 

 which arose could be satisfactorily answered by the work of a single year. 

 During the summer of 1905 the hospitality of the same Institution, cour- 

 teously extended through the director of the Tortugas Laboratory, made it 

 possible to continue stud}- upon some of the same questions in subtropical 

 waters, and the following sections present the data accumulated at that time. 

 It is a pleasure to acknowledge that the facilities liberally and wisely pro- 

 vided by the laboratory, and the stimulating interest and helpful sugges- 

 tions of the director were of the utmost assistance in carrying out the 

 research. 



CLADONEMA MAYERI, New Species. 



(Plates i and 2; Plate 4, figs. 21 and 22.) 



I. THE MEDUSA STAGE. 



CLADONEMA Dujardin, 1843. Ann. des Sci. Nat. 



CORYNE Gosse, 1853. Naturalist's Rambles on the Devonshire Coast. 



Generic characters. Anthomedusae of the family Cladonemidse, having 8 

 to 10 stout inflexible marginal tentacles arising from an ocellated basal bulb. 

 Tentacles bear terminally short prehensile processes, and usually also long, 

 branching, filamentous, nettling processes. Bell deep hemispherical. Manu- 

 brium long as height of bell, ending in 4 to 6 oral tentacles or knobs beset 

 with nematocysts. A circle of 4 to 6 gastric pouches located about half-way 

 up the mannbrium. Radial canals, 8 to 10, frequently arising in pairs 

 from single canals at top of manubrium. All of small size (under 4 mm. 

 in height of bell). 



Cladonema mayeri, new species. 1 



Specific characters. Cladonema with minute bell, 9 tentacles with both 

 prehensile processes and branching terminal filament. Radial canals, 6 at 

 origin, of which every other one bifurcates near the origin, making 9. 

 Tentacles weighted with concretions of spherical or rounded shape produced 

 and held within the endoderm cells of the larger part of the tentacle. Red- 

 dish-colored ocellus at the base of each tentacle. Manubrium with 6 gastric 

 pouches and 6 oral knobs of nettling organs. Velum wide and strong. 



Color lacking, except in the ocelli, which are reddish. Bell and ten- 



*The species is named in honor of Doctor Alfred Goldsborqugh Mayer, Director 

 of the Tortugas Laboratory of the Carnegie Institution of Washington. 



