of the Fishery Board for Scotland. 145 
the little rounded joint bearing the single hair is now the fourth, instead 
of third as in the Megalops, and also in another first young form. In 
Figs 21 and 23 the antenne of the right and left sides of a first young 
stage specimen are shown. In Fig. 23, however, the first two joints are 
not given. The antenna of the right side is incompletely developed. 
This may be in consequence of an injury, and the part may be in process 
of reproduction. The antenna of the left side was 9-jointed, but had 
not the two long hairs on the seventh joint. 
The first joint shows a recess in its outer surface, and behind it a 
tooth. A few more hairs are found on the first joint, and some of 
these are ciliated. 
The first three joints have scattered over their surfaces minute 
“needle-point ” cilia, which are arranged singly or in groups of 2, 3, 
or 4. ‘These cilia are an important character in the first young stage. 
MANDIBLE, mn, PI. vii. 
I. (Fig. 8). The Mandible is 1-jointed. It consists of two distinct 
parts, a cutting edge (e), and a massive crushing crown (cr). Alongside 
the crown a large triangular tooth (¢) rises in line with the cutting edge. 
There is no palp. Spence Bate drew attention to the resemblance 
between the mandible of the Zoéa of Carcinus and that of an amphipod. 
II. (Fig. 24), IIL. (Fig. 22), IV. (Fig. 9). In the remaining Zoéa 
stages the mandible retains the characters of the I. Zoéa. 
Mereatops (Fig. 26). The mandible is now very much changed. The 
cutting edge ends in a prominent stout angle. It has a rounded cutting 
edge and a 3-jointed palp. The palp (Fig. 26, 6) has on its end joint a 
series of seven stout short hairs, which are provided with stiff cilia 
(Fig. 27). The palp arises from the upper side of the mandible. 
1, (Fig. 10.) The inferior corner of the cutting edge is turned up, 
The hairs on the palp have increased in number. Otherwise the 
mandible is little changed. ‘The figure shows the upper surface. 
Labrum, lr. Labiuwm, lb. Plate vii. 
The labrum of I. Zoéa is shown in Fig. 33; the labium is seen in 
Fig. 25. 
First Maxiiia, lm, Plates vii. and viii. 
I. (Fig. 14). The first maxilla has a 2-jointed protopodite. The 
inner edge of each lobe is furnished with toothed spines. Rising from 
the second joint there is a 2-jointed palp. 
The palp bears at its extremity six stiff blunt hairs, one of which has 
on its proximal half a few long cilia. Of the others one or two are 
minutely serrated (Fig. 34,a). There is a similar hair on the first joint 
of the palp. 
The spines on the protopodite lobes are strong, with large teeth or 
stout lanceolate cilia. On the upper lobe there are five spines ; on the 
lower lobe there are seven. The latter are provided with long lanceolate 
cilia, as are also certain of the spines of the upper lobe. Figs. 31, 32, 
and 34, b, ¢, are spines of the protopodite lobes. The spines are similar 
to those found on the first maxilla of the Zoéa of Crangon vulgaris. 
On the lower edge of the upper lobe there were three groups of cilia. 
They were not noticed in the other Zoéa stages, 
II. (Fig. 37). The first maxilla has gained a number of spines, 
eight being present on each lobe. On the outer edge of the upper 
K 
