56 



HYDROIDA 



iiig, in larger colonies of Pcrigoniiiius^ individnals with psendohydrothecae bnlging even more loosely 

 ronnd the shrunken and contracted polyps than that rendered in Kramp's drawing, while, at the 

 same time, in extended polyps in the same colony, a superficial view fails to notice tlie presence of 

 this formation (Broch 1911, fig. 12). The intermediate state represented by Jaderholm is the com- 

 monest observed in preserved colonies. Still one point of difference might seem, to remain, the chiti- 

 nons cup in which the gonophore, in Garvcia grociiLandica, is resting when it is about to empty its 

 ripe contents. This cup, or rather this remnant of the flayed-off external periderm cover of the gono- 

 phore, is, however, frequently observed also in the female gonophores of t^-pical Pcrigonimus rosnis; 

 in which hitherto no particular importance has been attached to this character. Accordingly, we have 

 to include Garvcia groeiilandica as a s^-nonyme under Pfn'goiniinis rosciis. 



The chief occurrence of the species is attached to the middle and the lower parts of the literal 

 region of the boreal waters. It occurs rather frequently from Bohuslan as far as Lofoten, generally 

 attached to stalks of Ttthiilaria iiidivisa. However the species also penetrates far into Arctic waters, 

 and has been recorded from the White Sea and as far to the north as Nova Zembla. It has previ- 

 ously been recorded from Greenland (Jaderholm 1909), where now also Lille Hellefiskebanke, Fiske- 

 nes (West Greenland), and Danmarks Havn (East Greenland) have to be added to its localities 

 (Text-fig. R). 



Family Eudendriidae. 



Hydroids forming colonies, the polyps of which are provided with a single whorl of filiform 

 tentacles. The proboscis is capitate, placed with a narrow base on the broad polyp body above the 

 tentacle whorl; the stinging cells of the tentacles are small and rodshaped. Also larger stinging cells, 

 narrowly oval, occur, particularly in the sjjecific stinging organs of the polyp. The stinging cells of the 

 tentacles are arranged in very distinctive transverse belts. The polyps are wholly naked. The endoderm 

 of the polyp is differentiated into two portions, an oral portion, consisting of small-nucleated, indifferent 

 cells, among which occur some mucous gland cells, and the proper gastral portion. The limit is formed 

 b\- the tentacle whorl. The tentacles lack a central cavity. The colonies have no calcareous skeleton. 



Nearly all investigators of hydroids have distinguished the Endoidriidac as a family of their 

 own. To this Levins en (1892) forms an exception, considering the arrangement of the tentacles in 

 a single whorl round the poh'p as indicative of so near a relationship to the BougaiiivilUidar that he 

 unites the two families into one. However, the Eitdciidriidar^ in their structure of the polyps, show, 

 as compared to other athecate hj-droids, such peculiarities that we are forced to distinguish them as 

 a family of their own. In the first place are obvious the broad structure of the pohp bod\' and the 

 capitate proboscis, placed with a narrow base above the well defined tentacle portion. In this cha- 

 racter the polyps bear a strongly marked resemblance to the thecaphore Campa-unlariidae. This like- 

 ness is the more interesting because, in the more delicate structure of the polyp of the Etidcndriidac, 

 several points of resemblance to the thecaphore hydroids are demonstrable. Thus the stinging ceils of 

 the tentacles of Eitdcitdriidac^ as well as those of the thecaphore h)droids, are arranged in well defined 



