SCYPHOMEDUSAE 393 



ADDITIONAL REMARKS ON THE PIGMENT OF 

 FRESH MATERIAL 



Dr Kemp was kind enough to send me some specimens of Periphylla hyacinthina and 

 Atolla wyvillei collected during the last cruise of the ' Discovery II ' in the years 193 1-3, 

 and I have thus had the opportunity to study the brilliant colours of fresh material only 

 one or two years old. 



One specimen of Atolla wyvillei forma bairdi, St. WS 612, 750-0 m., is especially 

 interesting. It is 20 mm. in diameter, including the lappet zone, and the height is 

 55 mm. The whole exumbrellar and subumbrellar surface of the medusa is covered with 

 a thin layer of a vivid reddish-brown pigment. The whole central disc and the lappets 

 (the latter on both sides), the whole subumbrellar surface, the ring muscle and the 

 tentacles are brilliantly coloured ; but the epithelium is extremely fragile and falls off 

 at the slightest touch. The stomach is very dark purple brownish-red, of the colour of 

 coagulated blood. Actually the whole surface of the medusa is pigmented and the central 

 disc is not transparent and colourless as believed hitherto. The tint is a bright reddish 

 brown, a little darker in the furrows of the central disc, in the central furrow and 

 between the pedalia. 



Four large specimens of Periphylla hyamithina typica, or rather transitional stages to 

 forma hyacinthina, from Sts. 539, 716, 1023, 1147, from 0-212 m., show pigmentation 

 similar to the strangely coloured specimen from St. WS 552 B, mentioned above (pp. 

 347' 357)- They have a bluish-red stomach, not so deeply pigmented with purple-brown 

 as usual, the lappet zone transparent white, tentacle muscles, tentacles and rhopalia 

 yellowish brown. The pigment on the tentacles is extremely delicate and falls off very 

 easily, so that the mother-of-pearl underlayer becomes visible. The stomach is dark purple 

 with a bluish tint, darkest in the uppermost parts (" acrogaster ") in the neighbourhood 

 of the " Stielcanal", becoming less pigmented, more transparent reddish-blue, in the 

 vicinity of the coronal furrow. The walls of the subgenital porticus are transparent and 

 without any trace of pigment. In three specimens the stomach is somewhat tent- 

 shaped, showing the 8-rayed star formed by the stomach-pockets, but rather less dis- 

 tinct than described by me in the much larger specimens of regina. 



One specimen of Atolla wyvillei forma verrilli from St. 1 179, 40 mm. in diameter and 

 much faded, is very peculiar; its annular zone is extremely broad, nearly as broad as the 

 height of the central disc. 



The localities from which these additional specimens were obtained are as follows : 



