226 



ACTINIARIA 



figure of the sphincter of A.walteri, reproduced by Kwietniewski (1898) — a species to my mind identi- 

 cal with A . spetshergensis — the sphincter seems to be almost alveolar. In sexually ripe specimens I have 

 but rarely found traces of stratification in the middle part ; this stratification is, however, never as distinct 

 as in Adinostola abyssorum and callosa. 



The mesenteries are arranged as in the type-specimen, which I ha\^e been able to confirm by several 

 examined specimens. The longitudinal muscles of the strongest mesentery in the pairs of the third cycle face 

 towards the mesenteries of the first cycle. In a single specimen, of which I have examined one half, two mesen- 

 teries deviate from this rule, in as nuich as the longitudinal muscles face 

 towards the mesenteries of the second order. The appearance of the 

 mesenteries as for the rest agrees w^th that of the type-specimen. The 

 size of the marginal stomata, however, varies considerably, some- 

 times they are very large as in the reproduced specimen of A . sibirica 

 (Carlgren 1893b p. 233 fig. i), at other times they are small as in the 

 type-specimen. The ciliated streaks were well developed and the meso- 

 gloea of the filaments in the middle part provided with rather numer- 

 ous cells. 



The reproductive organs start from the mesenteries of the third 

 order ; in a specimen I have, however, found a fertile mesentery of the 

 second order. In a great part of the specimen the ova were large and 

 few, in other parts numerous and smaller. This difference is probably 

 connected with the fact that the reproductive period in the first case 

 had come to its close. I have in several specimens found young in 

 the coelenteric cavity. Sometimes these young reach a considerable 

 size (Carlgren 1893b, 1902 p. 47). The coelenteric cavity thus in 

 this species serves as a brood-room. 



As I have before mentioned (1902 p. 47) a parasitic Crus- 

 tacean, probably Antheachares diibenii, sometimes appears in the 

 mesenteries. Sometimes a Nemertin, Nemertopsis actinophila Biirger, seems to live symbiotically with this 

 species. From the mouth of a specimen from Coal bay, Spitzbergen such a Nemertin juts out, quite unhurt. 

 Systematic remarks: As is seen by the list of synonyms, I think that Adinostola sibirica Carlgr. 

 and A. walteri Kwietn. are identical with A. spetsbergensis. The few differences I have found between A. 

 sibirica and spetsbergensis do not justify the formation of a new species for sibirica, as the appearance of the 

 sphincter, of the column and of the stomata may vary. The same is the case with A. walteri. Probably Kya- 

 thactis hyalina Dan. is identical with A. spetsbergensis and is only a young of this species; of this I have con- 

 vmced myself by a comparison of a specimen of this species with young of A. spetsbergensis. I reproduce 

 here a transverse section of the sphincter of Kyathactis (fig. 208). Upon all accounts, A', hyalina is an Actino- 

 sto/a-species and nearly related to A . spetsbergensis. 



Textfig. 208 



AcHnoslola (Kyathactis) hyalina. 

 Transverse .section of .sphincter. 



