ttVDliOlDA .ft 



there are in the colonies also numerous blastostyles, which are wholly devoid of rudiments of tentacles 

 and accordingly only forming a stalk in the same way as is indicated by the diagnosis of Bounevie. 

 Rut there always occurs a small pohp, and a "complete atrophy" of the polyp is in no case demon- 

 strable; nor is it obvious from the imperfect figure of Bonne vie (1899, Tab. I, Fig. 3). — The great 

 variation of the blastostyles of the original specimens dcterniincd by Bergh, shows us that the 

 species stated by Bounevie may be founded on a colony where tlie blastostyles carrying tentacles 

 were reduced to a miuimiun in number. But this does not give sufficient reason for maintaining it 

 as a 2:)eculiar species beside Ilydractiiiia carica. 



Flydractiiiia carica is an Arctic litoral species, which, in boreal waters, proves able to penetrate 

 along the West coast of Norway as far as Bergen (Text-fig. M). It has been found elsewhere only 

 in high arctic regions, in the Kara Sea, in the Murman Sea, and at vSpitzbergen. It has also been re- 

 corded by Jaderholm (1909) from Davis Strait. 



Gen. Bougainvillia Lesson. 



Upright colonies witli branched hydrocauli clothed with a perisarc. The polyps are fusi- 

 form with the tentacles placed in a whorl below the conically pointed oral portion. The polyps are 

 naked without the slightest attempt at formation of pseudohydrotheca round their proximal portion. 

 The gonophores are placed on the stems of polyps fully developed or reduced (blastostyles). In the 

 latter case, the unbranched polyp stem will sometimes rise from tlie hydrorhiza instead of from tlie 

 hydrocaulus. 



A closer inquiry into the distinguisliing characters and tlieir systematic value, .shows us that there 

 is no reason to distribute the species of Boitgaiiivill/a on the three genera Boiiga iiivillia, Dicoryne^a.wA Hctcro- 

 cordylc. Sufficient cause for distinguishing between Bougai)iviUia and the two other genera is not at all 

 given by the fact that the former has medu.soid gonophores, while tlic two otiier genera have styloid go- 

 nophores. In mentioning the genera earlier treated, 1 have sufficiently explained the insignificance of this 

 criterion as to classification. Tlien remains the other distinguishing mark that the gonophores of Bougain- 

 villia develop on the stems of some fullgrown polyps, while in Dicoryiie and Ilctcrocordyk they are devel- 

 oped on the stems of reduced polyps (blastostyles). The genus Hydracliiiia shows us a full parallel to this 

 condition of things. But because of tlie many and close connecting links between one extreme and 

 the other, it has been agreed that the stronger and weaker .specializing into uouri.shing polyps and 

 blastostyles cannot be employed as a generic character. When, on the other liand, this lias been done 

 with Bougainvillia and Dicoryne and Helcrocordyh; the only reason must l)e tliat, between the few 

 species known of these genera, most of the links occurring in Ilydractiuia are wanting. This lack, 

 in fact, is not a sufficient rea.son to elevate, in one case, the character to an importance which is denied 

 in another case, even within the same family. It is not right to base the genera Bougainvillia, Di- 

 coryne and Hctcrocordylc on characters that must be used with discretion as specific characters 

 in Hydracliiiia. Further, as to tlie distinguishing mark between Dicoryne and Hetcrocordyle, it is 



still more diminutive. Hctcrocordylc coiiybcari A 1 1 m a n , the only species known of the genus, is so hke 



7 



The Ingolf-Expedition. V. 6. 



