8 DISCOVERY REPORTS 



Family Rathkeidae 



Rathkea africana sp.n. 



(PL I, fig. 5) 



Occurrence: St. 282. 12. viii. 27. 01' 11' S, 05° 38' E. Gulf of Guinea, near St Thomas. Net: TYF 30o(-o) m. 

 I specimen, the holotype. 



Description. Height of umbrella 1-7 mm., diameter 1-2 mm. Umbrella almost cylindrical, evenly 

 vaulted at the top. Jelly very thin (probably shrunk by preservation), no apical projection and no 

 gastric peduncle. Manubrium about one-third as long as the umbrella cavity, cruciform in transverse 

 section. Gonads adradial, smooth, separated by deep grooves in the interradii. Small medusa buds 

 present on the lateral sides of the gonads. Oral lips bifurcated, each with two large and broad terminal 

 clusters of nematocysts ; no lateral clusters. Four radial canals and ring-canal very narrow ; velum ? 

 (crumpled). The eight marginal bulbs small, containing no pigment granules; three or four tentacles 

 in each of the perradial groups, two or three in the interradial. In each group, one of the tentacles, 

 the median one, large and stout, almost as long as the height of the umbrella; the second tentacle 

 about half as long, the third and fourth very small. 



In the preserved condition the medusa is colourless, apart from a distinct dark-brown line on either 

 side of the interradial grooves of the manubrium. 



This species differs from the northern Rathkea octopunctata, as well as from the subantarctic 

 R.formosissima, in the absence of an apical projection and a gastric peduncle; in the interradial division 

 of the gonads; in the narrow shape of the marginal bulbs, which are, moreover, destitute of pig- 

 mentation; further, in the very uneven size of the tentacles in each group. As far as the oral arms 

 are concerned, they are entirely different from those in R. formosissima, and in comparison with 

 R. octopunctata the oral arms of the present new species are considerably broader and they have 

 no lateral clusters of nematocysts. 



It would be a surprise to find either of these two species in a tropical locality like the Gulf of 

 Guinea. One tropical species of the genus, R. rubence, has recently been described from the south- 

 west coast of India by Nair (1951, p. 54, PI. I, figs. 2-3). It is very similar to R. octopunctata except 

 in the shape of the perradial corners of the mouth opening, which are ' developed into swollen lobes ' 

 and not drawn out into bifurcated mouth-arms. Thus the medusa from the Gulf of Guinea, Rathkea 

 africana sp.n., differs in several respects from all hitherto described species of this genus. 



Family BOUGAINVILLIIDAE 



Koellikerina maasi (Browne 191 o) 



1910 Koellikeria maasi Browne, p. 22. Pi. 4, figs. 1-5. 

 1912a Koellikeria waa« Vanhoffen, p. 361. PI. 25, fig. 2. 

 1939 Koellikerina maasi Kramp, p. 512. 



Occurrence: St. 1867. 10. xi. 36. 61° 37' 36" S, 43"^ 56' 06" W. Weddell Sea. Net: TYFH 500-450 m. 

 15 specimens. 



Owing to the contraction of the umbrella-margin in the specimens examined by him, Browne was 

 afraid that his figure of the entire medusa (1910, PI. 4, fig. 2) might not be quite correct; as a matter 

 of fact it is a perfect image of the present better-preserved specimens. I have nothing to add to 

 Browne's thorough description. 



Distribution. McMurdo Sound (Browne); Gauss Station (Vanhoffen). The occurrence of several 

 specimens in the Weddell Sea confirms the view that this is a truly antarctic species. 



