Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
15
Ligesom de fleste mucronella-arter er ogsaa denne
underkastet betydelig variation.
Paa høiarktiske eksemplarer kan zoöcierne naa en
usædvanlig størrelse. Paa en koloni fra St. 223 har jeg
saaledes maalt:
Zoöciets længde........1.2 mm.
„ bredde ,.......0.47 -
Mundingens bredde.......0.36
Aviculariets længde fra mandibelledet 0.2
„ bredde......0.12 -
Lignende maal har jeg taget paa en koloni fra
Jøkel-fjord (Kvænangen):
Zoöciets længde .1.0 mm.
,, bredde . . 0.42
-Mundingens bredde . 0.20
-Proximalrandens mucro er meget forskjellig i sin
udvikling, og mundingen kan tildels have et lepralia-lignende
udseende (fig. 15). Zoöciernes væg er i regelen tydelig
perforeret. Derimod kan oöcierne undertiden give indtryk
af at være hele (fig. 13), i andre tilfælde er perforeringen
paatagelig (fig. 14). Selv hos koloniel’ med ganske jevnbrede
zoöcier har jeg seet tydelige huller i oöcierne. Oöciernes
fonn 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
avicularierne danner som oftest en ret vinkel med zoöciets
længderetning. Hincks (9) har leveret en figur af sin art
Mucronella prælucida, som leder tanken hen paa
sincera-arten. Af denne sidste har Hincks muligens kun seet
7e/)/rt7/«-lignende former (se 10, tab 11. fig. 3), og da var
det naturligt at opstille prælncida som en egen art, men
har man seet i hvilken grad il/, sincera kan variere, bliver
man tilbøielig til at opfatte prælncida som en varietet af
denne. „The peculiar projections, placed on each side of
the cell-’ (Hincks, 11, p. 225) var muligens ikke fuldt
udviklede avicularier (se 9, tab. 4, fig. 1). og skulde den
formodning være rigtig, faar prælncida fra Queen Charlotte
Islands en paafaldende lighed med sinccra fra det nordlige
ishav. I ethvertfald er M. sincera udbredt fra Novaja
Semlja til Grønland, og fra Spitsbergen til Lofoten. Paa
mill reise vinteren 1899 tog jeg nemlig en koloni ved
Digermulen i Raftsundet.
Like most of the Mucronella 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 zoæcium..........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 . . 1.0 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 l^cpralia-Wkc
appearance (fig. 15). The wall of the zocecia 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
zocecia of equal breadth, 1 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
tapering, and the avicularia are generally at right angles
to the longitudinal axis of the zoæcium. Hincks (9) has
given a figure of this species Mucronella prælncida which
recalls the sincera species. It is possible that Hincks
has only seen forms resembling Lepralia (see 10, Pl. II,
fig. 3), and it would then he natural to make prælncida
into a special species; but any one who has seen to what
an extent M. sincera can vary, will lie inclined to look
upon prælncida as one of its varieties. "The peculiar
projections, placed on each side of the cell" (Hincks 11, p.
225), were possibly avicularia that were not fully developed
(see 9, Pl. IV, fig. 1); and should this supposition be
correct. the prælncida from Queen Charlotte Islands acquires
a striking resemblance to the sincera from the northern polar
sea. In any case, ^f. 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 Digernnilen in Raftsund.
Gen. Palmicellaria.
(Jen. Palmicellaria.
Palmicellaria skenei, Ell. et Sol.
Eschara skenei var. tridens, Busk (3), p. 33. fig. 3.
Cellcpora tridens, Kirclienpauer (Bryozoa, 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.
Palmicellaria skenei. Ell. & Sol.
Eschara skenei var. tridens, Busk (3), p. 33, fig. 3.
Cellepora tridens, Kirclienpauer (Bryozoa, Die Expedition
zur physikalisch-chemischen und
biologi-schen Untersuchung der Nordsee im
Sommer 1872, 188, figs. a. b).
Occurrence. St. 290. 223, 323. 363.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
