52 AUGUSTA ÄENBÄCK-CHRISTIE-LINDE, NORTHERN AND ARCTIC INVERTEBRATES. 



Remarks. 



To the descriptions of Kilkenihalia borealis given before by Michaelsen (1904) 

 and Hartmeyer (1903) the following notes on the reproductive organs and the test 

 should be added. 



Testes as well as ovaries have been unknown hitherto, though the species has 

 been thoroughly investigated on that point by several eminent scientists. 



Reproductive Organs. 1 



The reproductive organs are in the form of a hermaphrodite structure, the 

 male glands as well as the ovary and the ducts being enclosed in a long, sac-like 



outgrowth of the mantle which extends into the com- 

 5 mon test. This outgrowth is here named the genital 

 pouch. 



In some individuals another sac-like structure, 

 generally of greater size, has been observed. It is 

 situated at the upper side of the above-mentioned one, 

 and projects like the latter into the common test. 

 When an individual contained developing embryos, 

 they were enclosed in this sac. No doubt it develops 

 t p . .-->■$ to receive the embryos, and it is consequently to be 



' 9P regarded as a brood-pouch (text-fig. 5). In the zooids 

 most advanced in development there are thus two 

 pouches which are to be referred to the reproductive 



Text-fig. 5. Kiikenthalia borealis Gott- ,pi q r*™ aq\ 



sohaldt. X23. The reproductive organs, Organs (rl. ö, lig. 4ÖJ. 



j. r> ^ u se o n fr f m th u outl ^ de - , . In the individuals examined, reproductive organs 



o. Bud. bp. Brood-pouch. gp. Genital pouch ' * ° 



with testis and ovary. have been observed only on the lef t side of the body ; 



they are placed ventrally, on the outer side of the 

 mantle, and are embedded in the test. 



Only one genital pouch — consequently only one brood-pouch — has been observed 

 in each zooid. If the individuals are seen from the inside of the colony, the position 

 as well as the number of the organs in question is easily determined. The members 

 of the colony are arranged in one layer and are placed close to each other side by 

 side; only the ventral part is free. From here the reproductive organs extend be- 

 tween the individuals, and only one genital pouch is visible between them, projecting 

 from the left side of each zooid. In the different zooids of the samy colony the 

 reproductive organs show various degrees of development. In some zooids the genital 

 pouch was very large and of considerable length, in others it was hardly distinguish- 

 able (ef. Pl. 3, fig. 49). A brood-pouch was developed only in few individuals. 



1 A preliminary note on the reproductive organs of Kiikenthalia borealis has been published in Proc. 

 Zool. Soc, London, 1921. 



