HYDROIDA 



*7 



A closer investigation of the living polyps and of their conditions very soon shows us that the 

 appearance of the polyp is varying very strongly according to its state of contraction. Now it is 

 stretched at length, assuming approximately the shape of a thin worm, now it is again contracted to 

 a short, thick lump, very nearly approaching the globular shape. Sometimes the polyp is at the widest 

 at the base; sometimes it is contracted in this part, so that the largest width appears farther out. 

 The study of the live polyps thus, in this case as in many others, shows us that many characters 

 which have been turned to account as criteria of species with the Coelenterata, may be of most doubt- 

 ful value or even of no importance whatever to classification. In the first place, of course, this is appli- 

 cable to the various states of contraction, which, in Coryne pusilla, have even led to subdivision into 

 several species. J ad er holm (1909) thus, on account of difference of shape of the polyp, still 

 distinguishes Coryne pitsilla and Coryne vermicularis Hi neks; as, however, all other characters wholly 



Text-fig. B. The distribution of Coryne pitsilla in the Northern Atlantic. 



agree, and the differences put to account as specific characters fall far within the limits of the polyp 

 movements described above from observation of living individuals, the separation into species cannot 

 be recognized; Coryne vermicularis forms a synonym of Coryne pitsilla and, in fact, only represents a 

 phase of the movement of the polyps. 



Coryne pitsilla has previously been recorded from the north of France, from Great Britain and 

 Ireland, from Helgoland, from Denmark, from Bohuslan, from the west coast of Norway, from the 

 Faroe Islands, and from Iceland (Reykjavik). In my material there also occurs a colony marked 

 "Greenland?", wrongly determined as Syncoryne mirabilis Agass; the species thus seems to belong to 

 the fauna of Greenland, but particulars are still missing. The rather numerous Icelandic colonies of 

 the species are all derived from the south-western point of the island. The species, accordingly, must 



The Ingolf-Expedition. V. 6. 3 



