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E. KAY LANKESTER. 
tinge and highly refringent character in the actual sections. The bilateral 
character of these plates is clearly seen, also their connection with the rods, 
and their “ thinning out ” at intervals ( e . g. Eig. 5, where the left endostylar 
plate is very thin, and Fig. 4, where it is practically absent). 
Following the sections according to their numbering, we see in the second 
the median endostylar artery, with its clot coloured black for diagrammatic 
purposes. The section traverses a free portion of the primary bar belonging 
to rod A, and within the endostylar area we see the posterior half of rod B 
on the one side, and the anterior half of rod C on the other side. 
In the third section (Fig. 6) we come across the junction of a tongue bar 
with the endostylar tract on the right side ; whilst the primary bar belonging 
to rod C on the left side is seen much in the same relation as is the primary 
bar belonging to rod A on the right side of Fig. 4. 
In the fourth section (Fig. 7) the tongue bar on the right side, and the 
primary bar on the left side, are cut more largely ; whilst a tongue bar extremity 
is seen on the left side also. 
In the fifth section (Fig. 8) the junction of the forks of two rods, C and D, 
is traversed on the left side (actual left, but right of the drawing) ; and the 
median artery is giving off a lateral branch to the incipient fork of the primary- 
bar rod B. 
In Fig. 9 the lateral vessel is more largely involved, the tongue bar of the 
right side is cut through its free region, and the tongue bar of the left side 
is seen in apposition to the endostylar tract. 
The whole series of figures serves to demonstrate the continuity of the 
coelomic space of the endostyle, with the pouch of the primary bars and with 
the cavity of the hollow rods of the tongue bars. 
Fig. 10. — a, b, c, d. Outlines showing various forms of distortion of the 
notochord, in transverse section, brought about by the action of reagents. 
Fig. 11. — Section through the fin-ray lymph-space of the first dorsal 
fin-ray, to show the bilateral base of the fin-ray and its consequent simi- 
larity to the double fin-rays of the ventral series between atriopore and anus. 
a. Epidermis. 1. Outer lamella of cutis, c. Gelatinous layer of cutis. 
d. Spaces in gelatinous layer of cutis, e. Inner lamella, with nucleated cells 
of cutis, f. Right and left basal pieces of the fin-ray. g. Fin-ray lymph 
compartment, h. Neural sheath. 
Fig. 12. — The twelve post-oral tentacles of Amphioxus or tentacles of the 
sphincter, seen from the post- oral surface. Drawn by Mr. Arthur Willey, 
student of University College, London, from a preparation made by him. 
These tentacles depend from the oral sphincter (velum of Huxley and 
Langerhans) into the pharynx, and are provided with numerous special sense- 
organs described by Langerhans (5). 
