40 Mr. G. Hodge on the Development of a Species of Pycnogon. 
a wonderful provision, the development of the terminal portion 
of the polypary into a polype is stayed (Pl. V. figs. 7 & 8), 
doubtless by the young Pyenogon availing itself of the nutrient 
matter circulating within the ccenosare as food, and thus with- 
drawing the material that should have developed a polype. The 
outer envelope or portion of the polypary (at this particular 
part) gradually enlarges, so as to assume the form and appear- 
ance before described, and the Pycnogon being comfortably 
housed amidst an abundant supply of food, nothing but time is 
requisite to enable it to undergo the necessary development. 
With such an abundant supply of food as must necessarily be 
presented to the young parasite within the Coryne, its growth 
must be rapid. At Pl. IV. fig. 10, I have represented one of the 
animals extracted from the sac. At this stage its size is much 
greater than the minute form before described : it now measures 
giz Inch across. An inspection of the figure will convey a pretty 
accurate idea of the appearance of the animal. It will be seen 
that the foot-jaws still retain their advanced state of develop- 
ment, as compared with the other portions, and the rostrum is 
still short and rudimentary. The foot-jaws were very active, 
opening and shutting in a highly excited manner, which was 
perhaps not to be wondered at when we consider the unceremo- 
nious way in which it was again introduced into the world. 
Within the rostrum, near its base, a peculiar pulsating move- 
ment is seen; further than this, no motion is discernible. 
The larva must have moulted, and got rid of the four 
rudimentary legs and their filamentous appendages ; for we here 
see that the young Pycnogon is destitute of legs (not a trace re- 
mains), and that the previously described process of the produe- 
tion of these organs by the gradual formation of lobes, to be sub- 
sequently elongated into leys, 1s again seen: there are now seven 
such lobes, three at each side and one opposite the rostrum, the 
latter showing 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. V. 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 im course of 
formation. At this stage there is an indication of the young 
Pyenogon being within a supplementary skin, external to the 
true skin: this appearance is best seen in the last joints of the 
legs. The growth of the terminal claw seems a work of time, 
the deposition of hard material being irregular and unequal. 
