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CHIYOMATSU ISHIKAWA. 
first and the second pairs and the inner branch of the two last 
terminate in two rudimentary spines. 
Within the branchiostegite two rudimentary gills are seen 
above the first and the second thoracic legs. The anterior is 
about three times as large as the posterior, and shows four simple 
lobes within it, while the posterior is as yet a simple sac. 
Blood-corpuscles are seen in rapid motion inside these gills. 
No trace of the abdominal appendages is as yet visible. 
Pigments. — Two large blotches of pigments are seen just 
behind the eye-stalks. Three smaller ones are also seen above 
the branchial chamber on each side of the carapace, and one on 
the median line of the abdomen. On the sternal aspect there 
is a large patch at the foot of the rostrum just above the 
ocellus, and a series of large median pigments are seen on the 
posterior part of each of the abdominal segments. On the last 
segment three patches are distributed, one above the anal 
opening and the two others on the two lobes of the fin. 
The Antennal Gland. — The first trace of this gland 
(figs. 68 and 90, gg.) becomes visible at the base of the second 
pair of antennae at the time when the first pair of maxillipedes 
appear in the embryo. The cells which are concerned in the 
formation of it are all ectodermic, and are at first about eight 
in number (fig. 90). They form a circular group near the 
inner side of the antenna. The median part of this is de- 
pressed, and forms a shallow cup-shaped cavity with a tolerably 
large mouth (fig. 91). The protoplasm of the cells that are 
thus depressed show granulations by which the area can be 
easily detected in the surface view. The depression becomes 
gradually deeper (fig. 92), while its opening gets smaller and 
becomes produced outward. The involution goes on still 
further. Granular fluid is already formed in the cavity, some- 
times before the hatching of the embryo. The canal formed 
by the involution becomes twisted round among the meso- 
dermic cells, and by the time the embryo is hatched its con- 
volutions are about three or four in number (figs. 93 and 94). 
Olfactory Setae. — At the stage of the embryo represented 
in fig. 79 the first trace of the olfactory setae becomes visible. 
