PYCNOGONIDA. 27 
ofits own, seven glands on each side of the animal, fig. 17a.a. Of Pa//. hastata I have two figures, pl. I, 
fig. 18—19, which show a more advanced stage, the third pair of ambulatory legs being here already 
very much lengthened, so that all three pairs seem to have been developed at the same time; from 
the first figure, however, it is distinctly seen, that there must have been an interval between the 
second and third pair. In the species of Psewdopallene the delay of the third pair of ambulatory legs, 
is, however, much more considerable, as is already shown by the two figures of Pseudop. spinipes, 
pl. I, fig. $—9. As to the further development I shall refer to the figures of Pseudop. circularis, pl. I, 
fig. 10—14. In the two first of these figures the development has not gone farther than to the re- 
presentation of Pseudop. spinipes, given in the preceding figure, but in fig. 12 it has gone much farther. 
Here the two foremost pairs of ambulatory legs have been fully developed (of the four uniform legs 
only the foremost right leg has been drawn), while the leg of the third pair is still only a bag-shaped 
process with a characteristic stiff bristle implanted on the upper side, a little before the point. In the 
same figure is furthermore seen the processes of the intestinal canal into the three pairs of legs, 
going in the wholly drawn foremost leg quite into the outermost joint. No traces of embryonal legs 
are seen, but neither, what is to be emphasized, is the least beginning of the imaginal fore limbs to 
be found. In the fore edge of the first abdominal ganglion, or the suboesophageal ganglion are seen 
through the epidermis a pair of short processes, as also a pair of still smaller, ballshaped appendages 
farther back, inside the side margin; but no nervous fibres are seen to arise from these processes and 
appendages. The anus is now distinctly open. Fig. 13 represents the same larva from the upper side, 
but with the two foremost pairs of ambulatory legs completely removed; the oculiferous tubercle with 
the eyes is distinctly seen. Fig. 14 gives the last phase of the same stage. Here also the third pair 
of ambulatory legs have been almost fully developed, only the last joint but one wanting; but still 
the lower side of the first segment of the trunk is as naked as in the preceding phase, fig. 12. 
Krøyer, in his second essay, Bidr. til Kundsk. om Pycnog. (1844), has given a description of 
what he calls the first and second stages of Pa/l/ene intermedia (== Pseudopallene circularis); but the 
description itself, and still more the figures in Gaimard's work of travel (1849) pl. 39, fig. 2 a. a.—d., of 
which figures Krøyer, no doubt, has been thinking, show distinctly that we here have two phases 
of the same larval stage, i. e. of the second stage, of which Krøyer treats, and the figures given by 
Krøyer of the animals, fig. 2, a. and c. are completely answering to my figures 8 and 12—13, only 
that in the first of my figures I have also the byssus-thread, and in the last one also the eyes. The 
omission of the eyes may, I think, be due to the bad preservation of the larva whereby the elements 
of sight have been removed from their position on the oculiferous tubercle; at least I believe to have 
found these elements strewn round in the trunk of the original piece of Krøyer which I have had 
occasion for examining, as well as the fresh specimen drawn here. Otherwise I think it to be the 
real or apparent want of genuine embryonal legs, and the contemporaneous development of the two 
foremost pairs of ambulatory legs, by which these latter get a certain resemblance to the former limbs, 
which has induced Krøyer not only to suppose this degree of the second larval stage to be the 
first, but also, what is much worse, led him to the wrong supposition of the real embryonal legs 
developing into the two foremost pairs of ambulatory legs. But this same mistake, on the other 
hand, has freed Krøyer from the present common wrong interpretation of the imaginal fore limbs 
4" 
