The Norwegian North- Atlantic Expedition. 85 



»The Zoanthodem arborescent, strongly branched. The basal 

 »part of the stem thick ; the main branches long, soft, and flexible ; 

 »they, either, ramify into branchlets, and these again into sev- 

 »eral stalks each carrying on its extremity several polyps, or they 

 »remain without any ramification, but then, also, carry on their 

 »extremity a collection of polyps which are, partly, concreted 

 »together at the base, partly, separated by a narrow sarcosonia. 

 »The polyps are non-retractile, short, but well developed, and are 

 »furnished with long, fusiform spicate spicules. The branches, and 

 »branchlets, noncalcareous. The spicules of the stem, partly, 

 »multi-radial short fusees, partly, plain bi-stellates invisible to the 

 »naked eye. Septa noncalcareous.« 



Subsequent examinations have shown the necessity of making 

 some changes in that generic character. There have, for instance, 

 been found, during the Norwegian North-Atlantic Expedition, no 

 less than 8 new species which I find must be assigned to the 

 genus Duva, although several of them differ from the generic 

 character originally stated, in the fact that calcareous spicules are 

 found, both, in the stem, and in the branches. I do not consider 

 it necessary to form a new genus for these because, with exception 

 of the calcareous deposit in the stem and branches, they have, 

 both in their external and internal structure, so much in common* 

 that a separation into two genera could not be maintained. 



To this has to be added that, in a few species, I have found 

 indications of transition stages, in so far that, either, in the stem, 

 or in the branches, there have been few, scattered, spicules, for 

 which reasons such colonies can scarcely be assigned to either of 

 the two genera, but must be situated intermediately between them. 

 But, in order to simplify the revision, I have considered it prudent 

 to classify the genus in two subdivisions — the one subdivision 

 including the species in which the greater part of the zoanthodem, 

 stem, and all the branches with their ramifications, are devoid of 

 spicules; and the other subdivision including the species in which 

 the entire zoanthodem is furnished with spicules. 



In consequence of this the generic characteristics of »Duva« 

 will, now, be stated thus: — 



The zoanthodem arborescent, ramous. The branches bare, for 

 a greater or lesser distance from the stem; become ramified 

 into branchlets, each of which carries on its extremity several 

 polyps, which are, partly, concreted together at the base, partly, 



