Summary[
edit] DescriptionAPI English: Anterior region of two pelagic larvae of
Amphioxus lanceolatus obtained by the tow-net in 8-10 fathoms, showing the asymmetry of the large lateral sinistral mouth with its ciliated margin
cm and the dextral series of simple primary gill-slits (1
ps-14
ps). The larvae swim normally like the adult or suspend themselves by their
flagella (not shown in the figures) vertically in mid-water. There is nothing in their mode of life which will afford an explanation of the asymmetry which is a developmental phenomenon.
Lettering of upper figure.â
anp, Anterior neural pore;
bc, rudiment of buccal skeleton;
c,
cilia;
cb, ciliated band;
cc, ciliated groove;
cm, cilia at margin of mouth;
gl, external opening of club-shaped gland;
Hn, Hatschek's nephridium;
lm, left metapleur;
n,
notochord;
pp, praeoral pit;
ps, primary gill-slits, 1, 5, and 13;
rm, right metapleur showing through.
Lettering of lower figure.â
a, Atrium;
al, alimentary canal;
bv, blood-vessel;
cv, cerebral vesicle;
df, dorsal section of myocoel (=fin spaces);
e, âeyespotâ;
end, endostyle;
gl, club-shaped gland;
lm, edge of left metapleur;
m, lower edge of mouth;
n, notochord;
nt, pigmented nerve tube;
ps, primary gill-slits, 1, 9, and 14;
rc, renal cells on atrial floor;
rm, edge of right metapleur;
so, sense organ opening into praeoral pit;
ss, thickenings, the rudiments of the row of secondary gill-slits. Illustration from 1911 Encyclopædia Britannica, article
Amphioxus. Date 15 January 2012 Source
Encyclopædia Britannica Eleventh Edition, Vol. 1, Page 890 Author Encyclopædia Britannica, 1911
