PHOXICHILIDIUM COCCINEUM. 183 
three at each side, and one opposite the rostrum, the latter show- 
ing a faint indication of division. The eyes, near the base of the 
rostrum, are also in course of formation; but at this period they 
are merely seen as a patch of colour. 
Passing onward to a further growth, we come to that stage 
when the young Pycnogon is found in the sac, with the legs 
doubled up, as shown at Pl. VIL., fig. 14. The several organs have 
now attained a considerable degree of development, and bear a 
close resemblance to the mature form. Fig. 15 represents the last 
joints of a leg, with the strong bristles in course of formation. 
At this stage there is an indication of the young Pycnogon being 
within a supplementary skin, external to the true skin: this ap- 
pearance is best seen in the last jomts of the legs. The growth 
of the terminal claw seems a work of time, the deposition of hard 
material being irregular and unequal. 
Haying traced, with some slight interruptions, the germs to 
the larvee, the larve to the immature and parasitical young, we 
now come to the concluding stages, viz., that period at which 
the young animal, well developed, and furnished with the neces- 
sary organs to enable it to provide for itself, seeks an exit from 
the Coryne-sac or vesicle: here the foot-jaws doubtless play a 
most important part. 
Such sacs as contain well-developed animals are found to be 
deeply tinged with colour near the summit: if these are selected 
and kept in clean and cool sea-water, the whole process may be 
watched. ‘The animal evidently uses its foot-jaws to rupture the 
investing skin of the sac, which at this stage, from some peculiar 
circumstance, seems more limp and pliable than at other times. 
An opening haying been effected, one or both of the claws of the 
first feet are projected through the opening, and, with the usual 
slow and languid movements of the class, are worked about, 
doubtless widening the breach; then another leg appears, and 
another, until the whole animal emerges and sprawls away. If 
we examine the figure of the free animal as seen shortly after 
its escape from the sac, it will be noticed that, aithough closely 
resembling the mature form in those features that guide us in 
the discrimination of the species, it nevertheless requires further 
