HYDROIDA 



17 



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 shaj^e 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 tlie base; sometimes it is contracted in this part, so tliat the largest width ap^iears farther out. 

 The study of the live po!\ps thus, in this case as in many others, shows us that many characters 

 which have l)een 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 Coryiic piisillo, have even led to subdivision into 

 several species. Jaderholm (1909) thus, on account of difference of shape of the polyp, still 

 distinguishes Coryiic pusilla and Coryiic vcrinicularis Hi neks; as, however, all other characters wholly 



Text-fig. B. The distribution of Coryne pusilla iu the Northern Atlantic. 



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

 movements described above from observation of living individuals, the sei^aration into species cannot 

 be recognized; Coryne vcrviicularis forms a synonym of Coryne pusilla and, in fact, oidy represents a 

 phase of the movement of the polyps. 



Coryne pusilla has previously been recorded from the north of I'rauce, from Great liritain and 

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

 Faroe Islands, and from Iceland (Reykja\'ik). In my material there also occurs a colony marked 

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

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

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



The Ingolf-ExpcJition. V. 6. 3 



