206 PERCY SLADEN TRUST EXPEDITION 



in size towards the margin. There is a considerable variation, both in shape and size of 

 the warts, due either to pressure or to a shrinkage of the jelly. The latter produces strange 

 effects, such as a wart having the appearance of being surmounted by a small capitate 

 tentacle, or the ex-umbrella being covered with tentacular-like papillae clearly visible to 

 the naked eye. It is quite easy to distinguish this species by the shape of the warts 

 provided that the specimens are in good condition, but there is a good chance of a failure 

 if the warts are squeezed out of shape by pressure. 



The description of Pelagia tahitiana by Agassiz and Mayer agrees so well with my 

 specimens that I cannot find anything of importance to add to it, and as Mayer considers 

 that Pelagia tahitiana is identical with Pelagia fiaveola of Eschscholtz I have followed 

 his synonymy. 



The size of the specimens in the " Sealark " collection is from 10 to 25 mm. in diameter 

 with the umbrella flattened out. A few large specimens have immature gonads hanging 

 down from the sub-umbrella. All the specimens are colourless in formaline, but they should 

 have been yellowish when alive. The oral arms of all the specimens are in bad condition. 

 They are apparently only very thinly covered with small patches of nematocysts upon slight 

 elevations of jelly. There is a small pit on the margin of the umbrella opposite each sense 

 organ. 



Some of the specimens have small barnacles attached to the ex-umbrella. 



Distribution. Tropical Pacific and Indian Oceans. 



48. Pelagia sp. ?. B. 



Locality. North of Chagos, Lat. 4°16'S., Long. rTSS'E. 75—0 fms. 17 May, 

 1905, B. 1 specimen. Surface. 18 May, 1905, B. 6 specimens. 75 — fms. 18 May, 

 1905, B. 2 specimens. 



The warts on the ex-umbrella of these specimens are low and roundish, with a broad 

 patch of nematocysts in the centre. These warts show no traces of ridges and furrows, 

 and none are oval-shaped as seen in Pelagia panopyra. In one specimen in a depression 

 at the top of the umbrella some of the warts are rather taller than the others, suggesting 

 a resemblance to the warts of Pelagia fiaveola. 



The specimens measured from 7 to 18 mm. in diameter. The umbrella has a flattish 

 top, nearly twice as broad as high and moderately thick. The marginal lappets are about 

 as long as broad, with rounded corners, and well covered with rounded patches of nema- 

 tocysts. The manubrium and oral arms are rather longer than in Pelagia panopyra and 

 thickly covered with roundish patches of warts. There is a shallow pit on the ex-umbrella, 

 opposite every sense organ. The gonads are only just beginning to develop in the larger 

 specimens. 



