ROSACEA MEDUSA. 203 



The only previous records from the Indo-Pacific, which could belong to 

 Rosacea plicata are the specimens from the Malaysian region, described by Lens 

 and Van Riemsdijk (:08) as '?Lilyopsis diphyes Vogt. 



Rosacea medusa (Metschnikoff.) 



Praya diphyes Graeffe, 'GO, p. 11, taf. 1, figs. 1-3 (non Kolliker, '53; Vogt, '54). 



Praya medusa Metschnikoff, '70, p. 925, pi. 1. 



Lilyopsis medusa Chun, '85, p. 280. 



Lityopsis rosacea Chun, '85, p. 280; Bedot, '96, p. 309, pi. 12, fig. 1. 



Praya sp. ? Fewkes, '80a, pi. 3, fig. 2. 



Praya blaino Fewkes, '83a, p. 845. 



Praya gracilis Fewkes, p. '83a, p. 841. 



Rosacea diphyes Schneider, '98, p. 81. 



? Lilyopsis catena Haeckel, '88b, p. 150. 



Station 4665, 300 fathoms to surface, one specimen. 



In the single specimen the two chief nectophores were still attached to each 

 other, but both were somewhat battered. Only a very much contracted portion 

 of the stem and appendages remains intact. So fragmentary is the latter that 

 I can give no account either of bracts or special nectophores, both of which 

 according to Graeffe ('60), Metschnikoff (70), and Chun ('85) are characteristic; 

 the latter especially so in the presence, on the margin, of the tentacular rudiments. 

 The nectophores are of equal size (11 mm. long), and similar in shape, both being 

 somewhat triangular, and obliquely truncate basally with proportionately large 

 nectosacs. So characteristic are these features, according to the figures and 

 accounts of all previous authors, that they serve as excellent field marks to dis- 

 tinguish this species either from R. plicata or from Praya cymbiformis (p. 200). 

 As indicated by Metschnikoff ('70) and by Bedot ('96, pi. 12, fig. 1), neither 

 nectophore encloses the other, but the two are merely closely opposed. The 

 hydroecial grooves are broad but very shallow, and extend the entire length of 

 the ventral surface, but, apparently, in life they do not form a closed tube 

 except near the anterior end. None of the older figures show these ventral 

 furrows clearly, but on the specimen studied they are plainly seen. The sub- 

 umbral canals, though fragmentary, are sufficiently preserved to show that their 

 course is a complex one, as observed by Chun and by Bedot, not straight as 

 Fewkes ('80a, pi. 3, fig. 2) represented them. 



In neither nectophore is there a distinct terminal dilation of the nemato- 

 cyst, such as has been figured by both Metschnikoff and Bedot; but the .shrivelled 

 condition of these organs has no doubt obscured their normal form. 



The records of the occurrence of this species: — Mediterranean (Graeffe, 

 Metschnikoff, Chun), Western Atlantic (Fewkes), Malaysian region (Bedot) 



