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21
og er ikke funden nordligere, end ved Bergen. Det er nu
til dette Dyr, Hamingia arctica slutter sig mest, idet den
danner en interessant Overgangsform; kun maa vi beklage,
at vi kun have havt 1 Exemplar til vore Undersøgelser.
Ydre Karakterer.
Legemet er cylindrisk med en glat, lidt slimet
Overflade, er 120mm langt, 20mm tykt paa Midten, men smalner
noget af mod begge Ender, Fig. 1.
Den forreste Ende er langstrakt, but afskaaren, og
paa den findes Mundaabningen, der danner en Spalte med
tykke, foldede Læber, og vender mod Bugfladen, Fig. 1, a,
2, a. Omkring Mundaabningen sees to halvmaaneformige
Hudfolder, Fig. 1, b, 2, b, der paa Rygfladen ere temmelig
fremspringende og staa et Stykke fra hinanden, imedens de
mere og mere nærme sig hinanden mod Bugfladen, hvor
den forreste Fold forener sig med den bagerste i en stump
Yinkel, Fig. 2. c, saa at dér bliver en liden Del af
Munden, der ikke omfattes af de’ nævnte Folder. Imellem den
forreste Fold og Munden er en yderst smal Indsynkning,
hvorved Mundlæberne blive ligesom mere fremtrædende,
Fig. 2, d; men imellem den forreste og bagerste Fold er
Indsynkningen baade bredere og dybere, Fig. 2, • e. Disse
Folder kunne vel betragtes som en rudimentær Snabel.
Omtrent 20mm fra Mundpartiet findes paa Bugsiden
to lange, cylindriske, krumbøiede Papiller, der staa ved
Siden af hinanden, og paa hvis fri Spids, der vender mod
Munddelen, iagttages en fin Aabning, Fig. 1, c, 2, /.
Kroppens bagerste Encle er afrundet, og i- dens
Centrum sees den runde Analaabning, Fig. 3.
Huden.
Huden er blød, halv gjennemsigtig, og dannes af en
yderst tynd, strukturløs Cuticula, Fig.. 4, a, der dækker
det hyaline Bindevævslag, som er temmelig bredt, og hvori
er leiret dels enkeltvis, dels i Grupper, Celler, Fig. 4, b,
5, a-, imellem hvilke sees uformede Pigmenthobe. Her
findes ikke noget Epithellag; men de nævnte Celler, der
som oftest ere fyldte med et finkornet, grønt Pigment, saa
at Kjernen ganske skjules, kunne i større Strækninger
være enkeltvis sammenhængende, og faar da et
epithellig-nende Udseende, Fig. 4, c, imedens tilgrændsende Steder
kunne være ganske blottede for Celler. Imellem disse
Pigmentceller, men som oftest dybere end dem, sees aflange
Bindevævslegemer.
Indenfor det hyaline Bindevævslag er Muskelhuden,
der bestaar af 3 distinkte Lag, nemlig Ringmuskler,
Længdemuskler og Skraamuskler.
Ringmusklerne ere de yderste og ligge nærmest det
hyaline Bindevævslag; de bestaa af smale Fibriller, der
coast, and has not been taken farther north than Bergen.
Now it is this animal with which Hamingia arctica exhibits
the closest agreement, representing a transition-form of very
considerable interest: we regret however to state, that.we
have had but one specimen whereupon to base our
observations.
External Characters.
Body cylindrical, with a smooth and slightly mucid
surface, 120mm long, 20""" thick in the middle, but
narrowing a little towards the extremities, fig. 1.
On the anterior extremity, which is elongate and
obtusely truncate, occurs the buccal opening, as a slit or
cleft, with thick, folded lips, facing the ventral surface,
figs. 1, a; 2, a. Round the buccal opening extend two
lunate cutaneous folds, figs. 1, b; 2> b, rather prominent
on the dorsal surface, and a little apart, whereas they
gradually converge on the ventral surface, and form an
obtuse angle, fig. 2, c, leaving a small portion of the mouth
which the said folds do not encircle. Between the anterior
fold and the mouth, occurs an exceedingly narrow
depression, which gives increased prominence to the buccal labia,
fig. 2, d; between the anterior and posterior folds, the
depression is broader and deeper, fig. 2, e. These folds may
be regarded as a rudimentary, proboscis.
About 20mm from the buccal region, on the ventral
surface, are seen two long, cylindrical, arcuate papillæ,
placed side by side, the free extremity of which, facing
the buccal section, is furnished with a minute aperture,
figs. 1, e; 2, /.
Posterior extremity of the body rounded, with the
anal orifice in the centre, fig. 3.
Skin.
The skin is soft, semi-translucent, and consists of an
exceedingly thin, structureless cuticle, -fig. 4, a, covering,
the hyaline layer of connective tissue, which is
comparatively broad, and has dispersed throughout it, either isolated
or in groups, a number of cells, figs. 4, b; 5, a, between
which are seen amorphous lumps of pigment. There is
no epithelial layer; but the cells are generally full of a
finely granulous, green pigment, by which the nucleus is
entirely hidden, and being sometimes connected, two and
two together, they resemble epithelium in appearance, fig.
4, c, whereas spots directly adjacent will be sometimes
altogether destitute of cells. Between these pigmentary cells,
but, as a rule, deeper down, are seen elliptical
corpuscles of connective tissue.
Underneath the hyaline layer of connective tissue,
extends the muscular integument, composed of 3 distinct
layers, viz. a layer of annular muscles, a layer of
longitudinal muscles, and a layer of oblique muscles.
The annular’ layer, adjoining the hyaline layer of
connective tissue, is the outermost; its muscles consist of
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