Dr, F. Miller on the Metamorphoses of the Prawns. 118 
length of the apical joint (the moveable finger) which still bears 
its terminal bristles. In the fourth and fifth pairs of thoracic 
feet also, the inner branch is now divided into four joints, and 
already somewhat exceeds the outer one in length. In animals 
45 mill. long, the fingers of the chelz are of equal length; on 
the fourth and fifth pairs of feet an acute process (the claw) is 
visible beside the terminal sete, and, especially in the fourth 
pair, the length of the true leg considerably exceeds that of the 
outer branch. 
The abdominal feet are recognizable as small mammille even in 
animals of 2°8 mill. in length; they are at first simple, and, as 
in the case of the thoracic feet, it is the outer branch that is 
first developed. In animals of 4°5 mill. in length, they are 
already of considerable size, but still without joints or sete, and 
the inner branch appears only as an insignificant appendage to 
the outer one. 
The first rudiments of the branchie are recognizable, in ani- 
mals below 4 mill. in length, in the form of small roundish 
excrescences at the base of the footjaws and chel, and subse- 
quently also on the fourth pair of thoracic feet. 
From the Mysis-like larva of 4°5 mill. in length there is but 
a small step to the Prawn-form. ‘The youngest animals ob- 
served in this form were 5 mill. long. Their frontal process had 
three teeth above. The antenne had undergone no change. 
The eyes no longer had any appendage: the median eye had 
become very indistinct. The upper lip had entirely lost its 
spine, and the mandibular palpi had acquired two jomts and 
short sete. The two anterior pairs of footjaws had approached 
close to the mouth, and become much shorter than the third 
pair. The outer branches of the thoracic feet, which are re- 
tained throngh life (as the so-called palpus flagelliformis) in 
many species of Peneus, had entirely disappeared. The abdo- 
minal feet had acquired joints and bristles (on the outer branch). 
The central plate of the caudal fan was diminished posteriorly, 
and bore on its straight posterior margin ten spines, of which 
those at the angles were the longest; on each lateral margin 
there were three shorter spines. The branchize (one over each 
fourth thoracic foot, and two over each of the preceding ones) 
were still elongated lamine with entire margins (they are 
plumosely cut in animals 9 mill. in length). The liver had 
begun to acquire a more composite form by the formation of 
new sacs and the ramification of the old ones. 
The animal was not observed more than 9-10 mill. in length. 
A second larva is readily distinguishable from the preceding, 
in the later Zoéa-form, by the fact that the anterior margin of 
Ann. & Mag. N, Hist, Serv.3. Vol. xiv. 8 
