56 AUGUSTA ÄRNBÄCK-CHRISTIE-LINDE, NORTHERN AND ARCTIC INVERTEBRATES. 



of Kukenthalia are quite different to those of the other members of the group. The 

 most striking difference is the presence of a brood-pouch in Kukenthalia, a structure 

 which, according to Michaelsen's investigations (1904), has not been found in the 

 other genera. Thus one might conclude that it occurs in the Arctic form only. 



As regards the genital pouch, the beginning of analogous structures may pos- 

 sibly be found in other genera, though they have not attained the same development 

 as in Kukenthalia. For instance, in Chorizocarpa sydneyensis and Chorizocarpa 

 michaelseni the reproductive organs are placed in cavities of the test. The description 

 of those species is, however, too incomplete to allow of a satisfactorj^ comparison. 



In certain respects Kukenthalia agrees with Gynandrocarpa. In both, the re- 

 productive organs consist of one single hermaphrodite structure. In Gynandrocarpa 

 it is placed on the right side, in Kukenthalia on the left. The structure of the 

 testis seems to be the same in principal. In both, it is composed of pyriform 

 vesicles with delicate ducts opening into sperm-ducts which generally unite into a 

 single vas deferens (ef. Herdman 1886, p. 332; Pl. 44, fig. 4). 



With regard to the branchial sac Kukenthalia shows a resemblance to Chorizo- 

 carpa and Diandrocarpa having no branchial folds, only a few longitudinal bars. 



If we compare Kukenthalia with the other Polyzoidae it is evident that it does 

 not belong to the forms pointing to a close relationship to the family Styelidae. On 

 the contrary, it seems to have more in common with the Botryllidae, even if such 

 common characters as the reproduetion by budding and the formation of colonies 

 should be left out of consideration. This view is based on the morphological cha- 

 racters exhibited by the branchial sac, the dorsal tuberele, the alimentary canal and, 

 judging from a preliminary investigation of mine of the Botryllidae, the reproductive 

 organs. 



K. borealis is an Arctic species widely distributed in the Arctic region, it even 

 occurs in the eastern Boreoarctic mixture zone — especially on the northern coast of 

 Norway — and the Faroe Islands form the southern boundary. But it has not been 

 recorded from the American Atlantic coast. It usually inhabits stony bottoms; 

 depth down to 550 m. 



