362 DISCOVERY REPORTS 



The small dodecabostrycha found in the Bellingshausen Sea and south of the South 

 Shetlands are remarkable. Never before has a small dodecabostrycha been found in 

 waters neighbouring the Antarctic continent. 



The geographical distribution gives no grounds for the opinion that the forms 

 dodecabostrycha, hyacinthina and reghia are geographical races. They all three live in the 

 same regions, which cannot be separated, and they have often been collected in the same 

 localities and even in the same hauls (see Maas, 1897). I have come to the conclusion 

 that they are different stages of growth of the same species, dodecabostrycha being the 

 youngest, hyacinthina forming the middle stage, and regina being the oldest stage of 

 development. The fact that the gonads of hyacinthina are always feebly developed, while 

 in the small dodecabostrycha and the large regina they are well developed, seems to be 

 unfavourable to this view. Previous authors (VanhoeflFen, Bigelow) took these characters 

 as a strong argument against the union of regina and dodecabostrycha. I believe that in 

 the young dodecabostrycha the gonads become mature, in the hyacinthina stage they 

 become reduced and in the regina stage they become mature again. In this way a rather 

 satisfactory explanation would be found for the fact that regina becomes mature so late, 

 for it is its second maturity. It would be similar to the case of ctenophores (dissogony). 



Bathymetrical distribution. (See Tables III and V.) Periphylla is represented in 

 the catches of the ' Discovery ' and ' William Scoresby ' at every depth from o to 2500 m. 

 If we observe the bathymetrical distribution of the different forms of Periphylla we find 

 that forma dodecabostrycha and hyacitithina are found more superficially than regina. 

 Dodecabostrycha is represented in these series by forty-one specimens, of which twenty- 

 three occur in depths of 750-1000 m., eight individuals have been found at depths of 

 iooo-i50om., and nine specimens in the upper strata. Forma hyacinthina (fifteen 

 specimens) has its maximum with ten specimens at the same depth as dodecabostrycha, 

 viz. in 750-1000 m. The transitional stages between these two, with thirteen individuals, 

 were caught mostly in more superficial layers from 1000 m. upwards. The forma regina, 

 represented by twenty-nine specimens, has its maximum (fourteen specimens) in 1250- 

 1500 m.; it occurs also in deeper strata (1500-1750 m. with five; in 1750-2000 m. with 

 four specimens). This agrees perfectly with Broch's statements (p. 9) on regina. In 

 these deeper layers dodecabostrycha and hyacinthina are almost entirely absent. The 

 intermediate stages between hyacinthina and regina (five specimens) live at a depth of 

 750-1750 m., and therefore in somewhat higher layers than regifta. 



Periphylla has not yet been found in the tropics in superficial layers ; in the Arctic 

 and sub-Antarctic regions on the contrary it is often at the surface (Bigelow, 1928). 

 Kramp (1924) found Periphylla in surface hauls in the Mediterranean and off the coasts 

 of Spain and Portugal in depths of 150 m. In the present material there are many hauls 

 from the tropics from a depth of 250-0 m.: viz. from Ascension (St. 288, 250-0 m.), 

 from the Gulf of Guinea (Sts. 285 and 276, from 125-175-0 and 150-0 m.) with forma 

 dodecabostrycha, with transitional stages to hyacinthina from St. 286, Gulf of Guinea, 

 and St. 270 Elephant Bay, both from 125-0 m., and hyacinthina typica from Sts. 276 and 



