48 



HYDROIDA 



with at Iceland. This specimen which was found on the north side of the island, was originally 

 recorded by Whither (1880), and has afterwards been revised by Saemuudsson (1902). It is a pecu- 

 liarity of the specimen that it is seated on the operculum of a Balanus Hdmmeri, and not on the 

 house of the Bernhardus crab. The species has been recorded once in the Arctic water-layers near Jan 

 Mayen (v. Lorenz 1886). In a previous work (1909) I gave utterance to the supposition that the 

 variety recorded by Levinsen (1892) had probably to be referred to the high-arctic species Hydrac- 

 tinia monocarpa Allman. An examination of the specimens mentioned, however, shows that this suppo- 

 sition is wrong. The specimens are unquestionable Hydractinia echinata with skeleton strongly deve- 

 loped. One of the specimens is distinguished by being attached to the shell of a living Buccinum 

 hydrophanum. The species, thus, proves able to occur now and then under wholly high-arctic conditions. 



Hydractinia carica Bergh. 

 1887 Hydractinia carica, Bergh, Goplepolyper fra Karahavet, p. 3, Taf. 28, Fig. 1. 

 1899 minuta, Bonuevie, Norske Nordhavs-Expedition, p. 48, Tab. I, Fig. 3. 



The reptant stolons are covered by a chitinous layer of coeuosarc, without small prides, but 

 bearing here and there vigorous spines, singly placed and up to 0.5 mm. high, conical with rounded 

 apex. The polyps attain a length of 2 mm., and have 10 — 14 rather vigorous tentacles jilaced in a 

 single whorl below the oral portion. Spiralzooids are not traceable. 



The gouophores are cryptomedusoid, placed, to a number of 3 — 6, round polyps almost wholly 

 atrophied, forming, if anything, only a short stalk, or showing rudiments of tentacles slightly indicated. 



Material : 



The Kara Sea: Petuchoffskoi Schar depth 7 fath. (the original specimen described by Bergh 1887). 



An examination of the original specimen, determined by Bergh, shows with full certainty 



that it is the same species that has afterwards been described by Bonne vie (1899) by the name of 



Hydractinia mimtta. The diagnoses, however, when compared, will show some points of difference. 



Bo nne vie does not mention the skeleton-formations at all while on the other hand, the statements 



of Bergh convey the impression of a greater resemblance to Hydractinia echinata than it really bears. 



Hydractinia carica lacks the small prickles found in the species last mentioned, and more vigorous spines 

 j— ^ •*/ ^V 



also occur rather scarcely; the latter (Tab. I, Fig. 11) are smooth and more conically tapering than those 

 i as 



of Hydractinia Sarsi. The main difference, however, between the diagnosis of Bonuevie and that 



of Bergh is implied in the mention of the blastostyles. Bergh states in his diagnosis "Sporosacs 

 borne on very short, rudimentary hydrants, without or with very few (1—4) tentacles", while in the 

 diagnosis of Bonuevie we find "Fixed gonophores without radial canals, from 3 to 5 in circle round 

 the inconspicuous blastostyles", and in her short comment Bonne vie further states that the species 

 is distinguished for "the complete atrophy of the gonophore-bearing hydranths". The specimens deter- 

 mined by Bergh show a great varying as to the development of the fertile polyp; it may, as he tells 

 us, have 1 — 4 tentacles; but they are a great deal more reduced than is apparent from his pictures, 

 and agree better with the drawings published by Jaderholm (1909, PL 2, Fig. 10 — n). However, 



