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8
gerne ved at passere igjennem de før beskrevne Zooiders
(Mødrenes) store Mundaabning; thi Sidekanalerne ere
lukkede baade for oven og neden.
Septum transversale, Fig. 12, d, er 6—7""" høit og
deler det nederste Parti af Bulbus i to Dele, nemlig i
Yen-tral- og Dorsalkanalen, hvoraf den sidste er videst. Hvor
Septum transversale ophører, 1—2’"’" fra Bunden, er altsaa
kun et Rum, Fig. 12, e, hvori begge de nysnævnte
Kanaler aabne sig.
Asen bøier sig i Dorsalkanalen 6—8""" fra Stilkens
Bund opad, danner en Anse, der er 10""" lang, 2—3"""
bred og ender haarfint.
Axeskeden, Fig. 13, g. 14, h, dannes af en temmelig
tyk Bindevævsmembran, hvori sees en Mængde
Ernærings-kanaler, Fig. 16, et, og som baade paa sin ydre og indre
Væg ere beklædte med Epithel. Den indre Væg er ved
stærke Bindevævstraacle fæstet til Axens Outicula. Denne
er saa stærkt adhæreret til Axen, at den ikke kan løsnes
fra samme uden at rives istykker. Hvor
Sammenvoxnin-gen finder Sted, iagttages en Række af næsten firkantede
Celler, hvori sees en liden, rund Kjerne, Fig. 15, a.
Axen er paa den nederste Del af Rachis, der hvor
Zooidestriben tager sin Begyndelse, 0,267’""’ bred. Dens
Grundniasse bestaar af fibrillært Bindevæv, som danner
tætte Lag af koncentriske Ringe, hvoraf nogle synes at
være tykkere end andre, Fig. 15, b, og hvorimellem sees
tykke, temmelig tætliggende, radiære Fibre, Fig. 15, c. 16, b.
Disse radiære Fibre straale ud fra Axens Peripheri,
nemlig fra Cuticula henimod Centralstramgen, hvor de ophøre.
Centralstrængen er elliptisk, 0,071"1"’bred, og dannes af to
Lag, et lysere, ydre, Fig. 16, c, og et noget mørkere,
indre, Fig. 16, d. I Midten af det indre Lag saaes
paa flere Tversnit en rund Aabning, som tydede hen paa
en tilstedeværende Centralkanal, der sandsynligvis opfyldes
mere eller mindre af Kalkkorn, som forøvrigt ere afsatte i
den hele Centralstræng. Axen er overalt gjennemtrængt
af fine Kalkkorn, og det er kun ved at fjerne disse, at
dens Bindevævsstruktur kan iagttages.
Udenfor Axen findes ikke Kalk hos Slægten Svava.
Slægtskarakter.
Smaa Søfjære med rudimentære Finner; en
Zooide-stribe paa liver Side af Stilken, hvor
Generationsorga-nerne rage ind i de to Sidekanaler og udvikle der
Kjøns-produktet. Kalkaxen har en elliptisk Centralstræng og er
rig paa radiære Fibre. Sarcosoma, Celler, Polyper uden
Kalk.
able to ascertain, the young ones are born, by passing
through the previously described large zooidal (the
maternal) oral aperture; because, the lateral canals are closed
both above and below.
The transversal septum (fig. 12, d) is 6—7""" high,
and divides the lower portion of the bulb into two parts;
namely, the ventral, and the dorsal canal, of which, the last
named, is the widest. Where the transversal septum
ceases, 1—2""" from the bottom, there is, therefore, only a
space (fig. 12, e) in which both the canals just spoken of
debouch.
The axis becomes curved in the dorsal canal, 6—8"""
from the base of the stem. Upwards, it forms a hook,
which is 10""" long, 2—3""" broad, and terminates fine as
a hair.
The sheath of the axis (fig. 13, ff. 14, h) is formed
of a pretty thick connective-tissue membrane, in which, a
multitude of nutrient canals (fig. 16, a), is seen, and which
are clad, both on their inner and outer walls, with
epithelium.
The inner wall is attached to the cuticula of the
axis, by strong filaments of connective-tissue. The cuticula
is so strongly adherent to the axis, that it cannot be
separated from it, without being torn in pieces. Where the
concretion takes place, a series of nearly quadrangular
cells is seen, in which a small round nucleus is observed
(fig. 15, a).
At the lower part of the rachis; where the zooidal
stripe commences; the axis is 0.267""" broad. It’s
component substance consists, of fibrillous connectiv#-tissue, which
forms close layers of concentric rings, of which, some
appear to be thicker than others, (fig. 15, b) and between
which; thick, rather closely set, radiating fibres are seen
(figs. 13, c. 16, b). These radiate fibres proceed from the
periphery of the axis; namely, from the cuticula towards
the central cord, and there cease. The central cord is
elliptic, 0.071""" broad; and, is formed of two layers, a
bright one, (the outer one) (fig. 16, r), and a somewhat
darker one, (the inner one) (fig. 16, d). In several sections,
a round opening was seen in the middle of the inner
layer; that suggested the presence of a central canal,
probably, more or less, filled up with calcareous granules,
which, otherwise, are found deposited in the entire central
cord. The axis is, everywhere, penetrated, by minute
calcareous granules, and, it is only upon removing these,
that its connective-tissue structure can be observed.
Except in the axis, lime is not found in the genus
Svava.
Generic Character.
Small sea-pens, with rudimentary fins. A zooidal
stripe on each side of the stem, where the generative
organs project into the two lateral canal?;, and there
devel-ope the sexual product. The calcareous axis has an
elliptic central cord, and is rich in radiate fibre. The
sarcosoma. cells, and polyps are all non-calcareous.
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