2 MARIE V. LEBOUR. 
young nauplius stage the feelers differ in being long and thin in Calanus 
finmarchicus and short and hook-like in Pseudocalanus elongatus. 
Nauplius Stage III is much the commonest stage and occurred all the 
time the material was being examined. The animal probably stays some 
time in this stage. 
The number of bristles on the antennules of the nauplius is a sure 
guide to the stage, as they are constant and very easily seen. They also 
agree exactly in number with similar stages in Pseudocalanus and Para- 
calanus. 
The colouring was much the same throughout all the stages, although 
not so marked in the early nauphus. The first nauplius stage has pigment 
present only in the region of the alimentary canal, where a few orange and 
red spots occur, and the tips of the appendages are a light orange. Later 
on the colouring is more marked. In the first copepodid stages and after 
the antennules are beautifully spotted with dark red, the bristles being 
red, and the furcal bristles are red merging into orange ; the tips of the 
antenne and mandibles are red, and the distal portions of all the appen- 
dages as far as the maxilhpeds and also the hind end of the body are 
yellow. This colouring appears in all the copepodid stages with slight 
variations. 
Grobben’s descriptions agree well with the present material. Those 
stages which he figures are probably I, III, IV or V, and VI, also the first 
copepodid stage. 
THE NAUPLIUS. 
Stace I (Plate 1, Fig. 1). Only one specimen. This is very lke 
Grobben’s figure of the early nauplius, but he figures only 2 bristles on the 
antennule where the present specimen has 3. It appears to be an earlier 
stage than any of Oberg’s. His Stage I of Pseudocalanus agrees with 
Stage II of the present species. His Stages III—V agree with the corre- 
sponding stages of Calanus as described in the present paper. Length of 
body 0-21 mm., oval, slightly more pointed posteriorly than anteriorly, 
faintly pik with orange tips to the appendages. Eye dark red. A pair 
of thin feelers at the hind end of the body. 
Appendage I. ANTENNULE (Plate 2, Fig. 1). The end segment divided 
off, the other 2 merely indicated. A small bristle just behind the end 
segment, the latter bearing 3 bristles. 
Appendage II. Anrenwna (Plate 2, Fig. 6). 
Coxopodite with a large thorn-like masticatory process. 
Basivpodite with 2 roundish prominences, the proximal portion with 
2 small bristles. 
