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4
at Mundskiven faar Udseende af et Hoved, der altid bøier
sig mod Bugfladen, Fig. 2.
Noget foran Kraven, som oftest skjult af denne, sees
to meget smaa Aabninger, skilte fra hinanden ved en
liden Fold, af hvilke den for Grenerations-Organets
Udfør-selskanal er lidt fremspringende, imedens den anden, der
fører ind til Stenkanalen, er i Niveau med Huden. Paa
Rygsidens bagerste Del findes den store, runde
Kloakaab-ning, Fig. 1, b.
Paa begge Sider af Kroppen, just der hvor Bug
og Ryg støde sammen, sees en Række tykke, lange,
koniske Fødder, der fortsættes omkring Dyrets bagerste
afrundede Ende, Fig. 2 c, c. I Regelen er der 5 paa
hver Side, og 6 omkring Enden, ialt 16; men paa et
Antal af 40 Exemplarer talte vi 18 Fødder paa et, og 14
paa to.
Fødderne ere paa Siderandene stillede ligeoverfor
hverandre, og det første Fodpar tager i Almindelighed sit
Udspring lidt bagenfor Kraven, — dog varierer dette noget;
thi hos enkelte staa første Fodpar ganske i Linie med
Kraven, imedens de hos andre staa temmelig fjernet fra den,
Fig. 1, 2. En lignende Variation finder ogsaa Sted med
Hensyn til Afstanden imellem Fødderne indbyrdes, saaledes
nemlig, at der stundom kan være »et stort Rum mellem
første og anden Fod, og hos enkelte andre staa disse
Fødder tættere sammen. De kunne ikke ganske indtrækkes,
og naar deres Spids indkrængedes, fremkom en Grube.
Ved Roden af hver Fod iagttages paa Bugfladen,
gjennem den temmelig klare Hud, en aflang Fodampulle,
Fig. 2, d, der ligger fæstet til den indre Hudflade, og fra
hvis indre Ende udgaa to Muskelbaand, der strække sig
hen til den midterste Længdemuskel, Fig. 2, e.
Legemets Overflade er ved 5 Længdemuskler delt i
5 Felter, 2 tilhørende Biviet, 3 Triviet. Disse
Længdemuskler have temmelig tykke Rande, men ere meget tynde
paa Midten, saa at den derunder liggende Nervetraad
skinner igjennem og giver sig tilkjende som en skarp Linie,
der ligesom deler Muskelen i to Dele, Fig. 2.
Huden.
Huden er meget gjennemsigtig, tynd, glat, blød, slimet
og kontraktil.
Cuticula er overordentlig tynd, vandklar, strukturløs
og tæt bunden til det underliggende Epithel eller
Subcuti-cularlag, hvoraf den er et Produkt, Fig. 10, a.
Epithelet bestaar af et Lag temmelig lange
Cylinderceller, som ere bredere ved Grunden, der er festet til
Corium, og smalere mod Cuticula, Fig. 10, b. Dels imel-
call it, the body grows narrower and more cylindrical,
forming, as it were, a neck, the anterior extremity of the
trunk having a somewhat greater breadth, which gives to
the oral disk the appearance of a head constantly inclining
towards the ventral surface, fig. 2.
A little in advance of the collar, by which as a rule
they are hidden, occur two minute openings, separated from
each other by a small intervening fold; one of these, the
genital pore, is somewhat gibbous, whereas the other, leading
to the "sand-canal," or madreporic tubercle, is in a plane
with the integument. On the posterior portion of the dorsal
surface occurs the large circular cloacum, or anal orifice,
flg. 1, b.
On ’either side of the body, exactly in the line of
junction of the dorsal and ventral regions, are seen a series
of long, thick, conic suckers, extending round the curved
posterior extremity of the animal, fig. 2, c, c. Most
individuals have 5 jon each side, and 6 bordering the extremity,
16 in all; but of 40 specimens examined, one had 18
suckers, and two, 14.
Along the lateral margins, these suckers are disposed
in opposite series, the first pair generally having its origin
a little posterior to the jugal protuberance; this, however,
is not a strictly constant feature, the first pair of suckers
being in some examples contiguous to the collar; whereas
in others, the space between is considerable, figs. 1; 2. A
corresponding variation as to distance characterises, too, the
arrangement of the suckers inter se; the first and second
suckers, for instance, are in some individuals comparatively
distant, but in others more closely set. They do not any
of them admit of being fully retracted, and on forcibly
invaginating the points, a small cavity or depression was
produced.
At the base of every sucker, on the’ ventral plane,
may be discerned through the semi-translucent membrane
an ovate pedal ampulla, fig. 2, d, attached to the inner
surface of the skin, from the inner extremity of which
two muscular bands are seen to issue, extending from
thence to the medial longitudinal muscle, fig. 2, e.
Five longitudinal muscles divide the upper surface of
the body into as many segments, two of which constitute
the bivium, and the remaining three the trivium. These
longitudinal muscles have thickish margins; but in the
middle they are exceedingly thin, and the nervous chord
beneath is distinctly perceived, bisecting, as it were, like a
sharply drawn line, the muscle it traverses, fig. 2.
Skin.
The integument is in a high degree translucent,
tenuous, soft, smooth, mucid, and contractile.
The cuticle is remarkably thin, pellucid, simple, and
closely webbed to the epithelium, or subcuticular stratum,
underlying it, of which indeed it is a product, fig. 10, a.
’The epithelium consists of a layer of comparatively
deep cylindric cells, somewhat broader at the base, which
is attached to the corium, than at the apex, or cuticular
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