204 PERCY SLADEN TRUST EXPEDITION 



The specimens are in bad condition. The smallest measured 7 mm. across the circular 

 muscle band, and it is an early stage, with 20 tentacles. The largest is 30 mm. in 

 diameter, across the circular muscle band and has 24 tentacles. The radial grooves on the 

 margin of the central disc are well marked and belong rather to the type associated with 

 Atolla vemllii than to Atolla wyvillei. 



SEM^OSTOME^. 



Genus Pelagia, Peron et Lesueur, 1809. 



Pelagia is one of the genera which has its species in a state of confusion. There has 

 been a general reduction in the number of species, and some of those which have been left 

 are still uncertain. The characters selected for the determination of the species have not 

 produced satisfactory results. 



The classification based upon the warts on the ex-umbrella failed owing to their being 

 treated too minutely, but I believe that they will yet prove useful for distinguishing races, 

 if not species. Warts vary considerably in shape and size in each individual, but there is 

 a predominating type which becomes characteristic of the race or species, and belongs to 

 that particular race only. The predominance of high conical warts is characteristic of 

 Pelagia Jlaveola. This type of wart does not occur in Pelagia panopyra, which has low 

 oval-shaped warts ; but minute roundish warts are common to both. 



The marginal lappets in all the specimens which I have seen are too much alike in 

 shape and size to be of any definite use for distinguishing species. The position and density 

 of the warts on the lappets may be useful for distinguishing races. 



Attempts have been made to distinguish species by the length and size of the 

 manubrium and oral arms, but one never knows when examining preserved specimens 

 how much the oral arms have contracted. 



In the "Sealark" collection there are three distinct kinds of Pelagia. Pelagia 

 jlaveola I am in favour of recognising as a distinct species on account of its peculiar 

 warts. » 



45. Pelagia panopyea (Peron et Lesueur) 1807. 



Pelagia panopyra, Bigelow, 1909, p. 43. 

 Pelagia panopyra, Mayer, 1910, p. 575. 

 Pelagia panopyra, Kishinouye, 1910, p. 9. 

 Pelagia panopyra, Bigelow, 1913, p. 88. 



Locality. South West of Chagos, Surface. 31 July, 1905. 5 specimens. 



The specimens from this station have warts on the ex-umbrella marked by ridges 

 and furrows. The warts form low mounds varying in shape from round to oval. The 

 oval-shaped warts predominate and are characteristic. The ridges and furrows are formed 

 in the jelly, and are clearly revealed where the ectodermal covering has been rubbed off. 

 An oval-shaped wart has a longitudinal ridge with lateral ridges and furrows running 



