PHIALIDIUM DISCOIDA. 155 



his single specimen was in such poor condition that he was unable to count 

 the otocysts with any certainty, being able to find only five, so that positive 

 generic identification was impossible. From its general form, and from the 

 form and extent of the gonads, I think it probable that it is either a Phialium 

 or a Encheilota, not a Mitrocomium ; but it differs from the present series 

 in having a large interradial bulb and from four to six small adradial bulbs 

 in each quadrant in addition to the four primary radial tentacles. Fewkes's 

 ('82'') account would suggest, as noted above, that this distinction was of 

 doubtful value, but from my own studies I conclude that it is probably quite 

 as significant in this genus as it is in Phialidium. 



Phialidium Leuckart, 1856. 

 Haeckel, 1879. 



Eucopidae with numerous otocysts, one or two between every two of the 

 numerous tentacles ; without marginal cirri or papillae ; no well-developed 

 peduncle. 



This genus has commonly been called Oceania by American authors, but 

 the name Phialidium is preferable in the interests of stable nomenclature, 

 because identification of the species to which Oceania was originally applied 

 is very doubtful ; while Oceania has been employed in widely different 

 senses by later authors (e. g. for Anthomedusae Vanhoffen, '89). 



The Atlantic species referable to this genus are so puzzling in their 

 synonomy, owing to their great variability, that they have long been a thorn 

 in the side of the student of Leptomedusae. The following species have been 

 described from the Pacific : — P. gregaria A. Agassiz ; P. pacifica Agassiz and 

 Mayer ; P. amhigua Agassiz and Mayer ; and P. hrunescens Bigelow. Another 

 Pacific species of Oceania, P. virens Bigelow (: 04), has since been made the 

 type of the new genus Phialucium by Maas (: 05). 



The present collection contains one species of the genus indistinguish- 

 able, on comparison with actual specimens, from the West Indian P. discoida 

 of Mayer. 



Phialidium discoida Mayer. 



Oceania discoida Mayer, : 00^ p. 51, pi. 20, figs. 53-55. 



Plate 6, Fig. 8 ; Plate 38, Figs. 6, 7. 



Acapulco Harbor; surface ; many specimens, 1 to 3.5 mm. in diameter. 

 The resemblance between these specimens and a collection of P. discoida 



