

Sfei 





T**/ 



15 



Ligesom de fleste nhucronetta-&rter er ogsaa denne 

 underkastet betydelig variation, 



Paa høiarktiske eksemplarer kan zoocierne naa en 

 usædvanlig størrelse. Paa en koloni fra St. 223 har jeg 

 saaledes maalt: 



Zoociets længde . . 1.2 mm. 



„ bredde , 0.47 - 



Mundingens bredde 0.36 - 



Aviculariets længde fra mandibelledet 0.2 



„ bredde ...... 0.12 - 



Lignende maal bar jeg tåget paa en koloni fra Jøkel- 

 fjord (Kvænangen) : 



Zoociets længde . .1.0 mm. 



„ bredde . . 0.42 - 



Mundingens bredde . 0.29 - 



Proximalrandens mucro er meget forskjellig i sin ud- 

 vikling, og mundingen kan tildels have et lepralia-Vignenåe 

 udseende (fig. 15). Zoociernes væg er i regelen tydelig 

 perforeret. Derimod kan oocierne undertiden give indtryk 

 af "at være hele (fig. 13), i andre tilfælde er perforeringen 

 paatagelig (fig. 14). Selv hos kolonier med ganske jevnbrede 

 zoocier har jeg seet tydelige huller i oocierne. Oociernes 

 form er heller ikke konstant, idet ganske kuglerunde kan 

 veksle med ovale. Avicularierne mangler i regelen, og 

 naar de forekommer sidder et dels paa høire side, dels 

 paa venstre side af mundingen, eller der kan ogsaa optræde 

 et paa hver side (fig. 14). Mandibelen er but, og avicu- 

 larierne danner som oftest en ret vinkel med zoociets 

 længderetning. Hincks (9) har leveret en figur af sin art 

 Mucronélla prælucida, som leder tanken hen paa sincera- 

 arten. Af denne sidste har Hincks muligens kun seet 

 lepralia-lignende former (se 10, tab 1.1. fig. 3), og da val- 

 det naturligt at opstille prælucida som en egen art, men 

 har man seet i hvilken grad M. sincera kan variere, bliver 

 man tilbøielig til at opfatte prælucida som en varietet af 

 denne. „The peculiar projections, placed on each side of 

 the cell" (Hincks, 11, p. 225) var muligens ikke fiildt ud- 

 viklede avicularier (se 9, tab. 4, fig. 1), og skulde den for- 

 modning være rigtig, faar prælucida fra Queen Charlotte 

 Islands en paafaidende lighed med sincera fra det nordlige 

 ishav. I ethvertfald er M. sincera udbredt fra Novaja 

 Semlja til Grønland, og fra Spitsbergen til Lofoten. Paa 

 min reise vinteren 1899 tog jeg nemlig en koloni ved Di- 

 germulen i Raftsundet. 



Gen. Palmicellaria. 



Palmicellaria skenei, Ell. et Sol. 



JEschara skenei var. tridens, Busk (3), p. 33, fig. 3. 



Cellepora tridens, Kirchenpauer (Biyozoa, Die Expedition 

 zur physikalisch-chemischen und biologi- 

 schen Untersuchung der Nordsee im 

 Sommer 1872, p. 188, fig. a, b). 



Findesteder. St, 290, 223, 323, 363. 



Like most of the Mucronélla species, this is subject 

 to considerable variation. 



In extreme arctic specimens, the zocecia sometimes 

 attain an unusual size. In one colony, for instance, from 

 Station 223, I have found the following measurements: 



Length of zocecium 1.2 mm. 



Breadth of zoæcium 0.48 - 



Breadth of aperture . . . . 0.36 - 



Length of avicularium from mandibular joint . 0.2 



Breadth of avicularium 0.12 - 



I have taken similar measurements from a colony 

 from Jøkel Fjord (Kvænangen): 



Length of zoæcium . . l.o mm. 

 Breadth of zoæcium . . 0,42 - 

 Breadth of aperture . . 0.29 - 

 The mucro of the proximal margin is very varied in 

 its development, and the mouth has sometimes a Lepralia-like 

 appearance (fig. 15). The wall of the zooecia is generally 

 perforated. The oæcia, on the other hand, sometimes give 

 the impression of being entire (fig. 13); in other cases the 

 perforations are evident (fig. 14). Even in colonies with 

 zoæcia of equal breadth, I have seen distinct holes in the 

 oæcia. Nor is the shape of the oæcia constant, as quite 

 spherical sometimes alternate with oval. The avicularia 

 are generally wanting, and when they occur, are situated 

 on the right, or the left of the aperture, or one may 

 appear on each side (fig. 14). The mandible is not tape- 

 ring, and the avicularia are generally at right angles 

 to the longitudinal axis of the zoæcium. Hincks (9) has 

 given a figure of this species Mucronélla prælucida which 

 recalls the sincera species. It is possible that Hincks 

 has only seen forms resembling Lepr alia (see 10, PI. II, 

 fig. 3), and it would then be natural to make prælucida 

 into a special species; but any one who has seen to what 

 an extent M. sincera can vary, will be inclined to look 

 upon prælutida as one of its varieties. "The peculiar pro- 

 jections, placed on each side of the cell" (Hincks 11, p. 

 225), were possibly avicularia that were not fully developed 

 (see 9, Pl. IY, fig. 1); and should this supposition be cor- 

 rect, the prælucida from Queen Charlotte Islands acquires 

 a striking resemblance to the sincera from the northern polar 

 sea. In any case, M. sincera is distributed from Novaja. 

 Semlja to Greenland, and from Spitsbergen to Lofoten. 

 While on my journey in the early part of 1899, I found 

 a colony at Digermulen in Raftsund. 



Gen. Palmicellaria. 



Palmicellaria skenei. Ell. & Sol. 



Eschara skenei var. tridens, Busk (3), p. 33, fig. 3. 

 Cellepora tridens, Kirchenpauer (Bryozoa, Die Expedition 

 zur physikalisch-chemischen und biologi- 



schen Untersuchung der Nordsee 

 Sommer 1872, p. 188, figs, a, b). 



Occurrence. St. 290, 223, 323, 363. 



im 



