44 EDWARD T. BROWNE. 
Dr. Mayer (1906) has described and figured some specimens of P. dodecabostrycha 
taken by the ‘ Albatross’ off the Hawaiian Islands in June, 1902, at the depth of 
577-480 fms. and 478-453 fms. The smallest specimen was 55 mm. high and 
50 mm. wide at the tentacular zone, and the largest 70 mm. high and 100 mm. wide. 
From the description and figures these specimens agree very well with those in the 
Antarctic collections. Mayer draws attention to the shape of the umbrella changing 
with age, becoming flatter and relatively wider as the Medusa grows larger. All the 
specimens taken by the ‘Albatross’ were deeply pigmented with brownish purple, 
especially in the zones of the radial and circular muscles. Mayer is of the opinion 
that it is possible that all of the so-called species of Periphylla may in the end prove 
to be local races of one and the same form. 
After the first examination of the specimens in the Antarctic collections I felt 
fairly sure that they were large specimens of Periphylla hyacinthina. My determination 
was based not so much upon the shape of the umbrella, or upon the amount of 
pigmentation, as upon the shape of the pedalia. All the specimens have the rhopaliar 
pedalia longer and narrower than the tentacular ones. In this respect they resemble 
Haeckel’s figures of P. hyacinthina. 
The rounded shape of the top of the umbrella is in favour of the specimens being 
Periphylla regina. But after comparing Dr. Wilson’s sketch (Plate VIL, fig. 1) with 
Agassiz’s sketch of P. regina, drawn and coloured from life (see Maas, 1897, Taf. X.), 
I came to the conclusion that the specimens did not belong to that species. According 
to Prof. Agassiz’s figure the pedalia of P. regina are semi-globular in shape, and all of 
the same size. 
At present the three species of Periphylla are mainly distinguished by the 
shape of the umbrella and by the colour and amount of pigmentation. I think 
that we require a better and more definite character for the determination 
of the species, especially as the identification has usually to be based upon preserved 
specimens. 
If Periphylla hyacinthina and P. dodecabostrycha be really distinct species, then 
I think a character could be found upon the margin of the umbrella, such as the shape 
of the pedalia, by which they could be readily distinguished. 
I have placed the specimens collected by the ‘Southern Cross’ and ‘ Discovery ’ 
under the name of Periphylla dodecabostrycha because they agree very well with 
Haeckel’s P. mirabilis, which is considered to be identical with P. dodecabostrycha. 
I am rather in favour of Mr. Bigelow’s suggestion that the small P. dodecabostrycha, 
described by Messrs. Maas and Vanhéffen, are young stages of P. hyacinthina. 
I am also inclined to think that the large specimens called P. mirabilis and 
P. dodecabostrycha will eventually be proved to be only very large specimens of 
P. hyacinthina. 
