of the Fishery Board for Scotland. 155 
escaped notice may be present. The fifth pereiopod is the shortest ; the 
propodite joint is shorter than in the second, third, and fourth limbs. 
The hairs on the dactylopodite are longer in the former than in the 
latter. 
As in the previous stage, only the part of the limb distal to the 
fracture plane is shown in most cases. Fig. 126 shows the complete 
fifth pereiopod, and Figs. 123 and 140 show two views of the coxopodite 
and proximal part of the basi-ischiopodite of the chela. Fig. 114 
represents an enlarged drawing of the coxopodite and basi-ischiopodite 
of the fifth pereiopod. 
BRANCHIA, br. 
The branchiz, as Claus* pointed out, are all appendages of the limb, 
and the positions which they occupy on the developing limb determine 
them as the future podobranchs, arthrobranchs, or pleurobranchs. In 
this connection, Claus wrote as follows:—‘ An jener entsprechen, die 
drei iibereinander sprossenden Kiemenknospen jedes Somiten gar nicht 
dem sinne der Huxley’schen Nomenclatur, sondern gehéren dem langges- 
treckten Basalglied an, von dem sich erst nachher der distale Theil 
als Coxalglied absetzt, wihrend der proximale mehr oder minder weit 
in die Wandung des Rumpfes aufgenommen wird,”* 
Compare also, in this connection, E. L. Bouvier :—‘“ Sur le developpe- 
ment embryonnaire des Galatheides du genre Diptychus.” Comptes 
Rendus Acad. Sc. Paris. exiv (1892). ; 
The branchie are not functional in the Zoéa stages. During the 
Zoéa period they are developing, and in the Megalops certain of them 
are functional. These are the two arthrobranchs attached to the chela 
and the two pleurobranchs of the second and third pereiopods ; 
they are completely cut up into lobes. The other gills—viz., those of 
the second and third maxillipedes— are not yet lobed. 
I, The rudiments of most of the gills can be seen in the I. Zoéa, 
they are all parts of appendages. The future branchie of the third 
maxillipede and of the pereiopods are all hollow outgrowths of he 
hollow rudiments of these appendages. In the I. Zoéa, then, we have 
the beginnings of the future arthrobranchs and pleurobranchs. On the 
third maxillipede and the chela are the buds of arthrobranchs, and on the 
second and third pereiopods buds of pleurobranchs. In Fig. 69, Pl. ix., 
a drawing of these is given. It is there seen that the gills of the second 
and third pereiopods (6r", b7'”) arise from the basal part of the limb- 
bud, while the large gill-rudiments of the chela (67’) and of the third 
maxillipede (67) arise farther up the limb-bud. In the former couple we 
have pleurobranchs, in the second arthrobranchs. The pleuron of the 
adult is formed out of the basal part of the limb; and this basal portion 
includes the gill in one case, and ends just at the gill in the other, so 
that the gill occupies a position between the limb and its basal part 
(pleuron). 
The large swellings of the third maxillipede and of the chela become 
each a pair of arthrobranchs. 
In one view of the second maxillipede (Fig. 85) a process of the first 
protopodite joint was seen (br ?). It may be the rudiment either of a 
gill or an epipodite, or what is not unlikely, of both. 
Il. (Figs. 84and 73). In the IT. Zoéa, on the third maxillipede there 
are now three swellings—the top one, an epipodite, the lower two, gills. 
The gill of the chela is still single. 
* Claus, ‘‘ Neue Beitriige zur Morphologie der Crustaceen.” Arb. a. d. Zool. Instit. 
Wien, T. vi., 1886. 6Taf., p. 1. 
