SCYPHOMEDUSAE 353 



a different and strange manner. I rather doubt whether the figure in question is 

 very accurate, not only regarding the pedalia but also in other respects (e.g. lack of 

 coronal furrow). 



The large broad Periphylla from the Hawaiian Islands, identified by Mayer (1906) as 

 dodecabostrycha and figured in pi. ii, fig. 6, with low dome, rounded stomach, no 

 " Stielcanal", deep coronal furrow and rather broad pedalia, next to fig. 5 of a young 

 specimen with sharply pointed bell, high vaulted stomach and "Stielcanal", might 

 equally have been identified as regina. Mayer thinks (p. 1137) that the shape of the 

 umbrella changes with age, becoming flatter and relatively wider as the medusa grows 

 larger. The principal reason for his identification may be that the pedalia are more 

 rectangular, not globular as they ought to be in regina. 



The same may be the case with the Periphylla figured by Vanhoeffen (1911, fig- i) 

 and identified as hyacinthina. 



Broch (19 1 3) studied nine specimens which he believed to be regina on account of 

 the rounded bell, the apex of the stomach being evenly rounded, with no trace of the 

 so-called " Stielcanal", and the pedaha more globular and less oblong than is usual in 

 hyacinthina. With regard to pigmentation he found no difference between this species 

 and hyacinthina. It is to be regretted that he did not give a figure of his so-called regina, 

 having had freshly preserved specimens in fair condition, and that he writes nothing 

 about the two doubtful specimens from St. 49 (500 m. depth) and from St. 81 (1500 m.). 



Bigelow (1928) in his Arcturus Report (pp. 495-6) mentions two specimens, also from 

 the tropical Pacific, which were precisely intermediate between hyacinthina and regina 

 because they had no " Stielcanal " and the pedalia showed the usual hyacinthina form — 

 thus combining the characters used by Broch for separating both forms. Bigelow gives 

 no figure. 



Resuming, / come to the conclusion that it is impossible to distinguish a large, so-called, 

 " dodecabostrycha " /row regina. / therefore restrict the name dodecabostrycha to small 

 flat specimens 0/35 mm. maximum dimiieter, zvith transparent peripheral zone; the name 

 hyacinthina to medium-sized specimens with pointed bell and stomach zvith more or less 

 pigmented peripheral zone; and the name regina to the large plump dome-like specimens. 



With regard to the few transitional stages between forma hyacinthina and regina 

 I must observe that I at first thought them to be developmental stages of regina. There 

 is, however, no necessity to do so. It is true they resemble the young larva figured by 

 Vanhoeffen (1908, pi. ii, fig. 8) ; but they are much larger ; the flat form of the bell and the 

 broad central disc are also found in dodecabostrycha ; there is no" Stielcanal ", though this 

 occurs also in hyacinthina, and the pedalia are always small and not relatively large as 

 they should be if we were in fact dealing with developmental stages of regina. Besides, 

 they are caught in strata more superficial than the habitat of regina. I therefore believe 

 these stages to be particularly low and deeply pigmented transitional stages between 

 hyacinthina and regina. 



To this discussion I wish to add some details, especially with regard to the large 

 specimens of the regina type in the present series. Short remarks have been given 



