28 PYCNOGONIDA. 
as direct continuations of the embryonal legs. For my part I must regard it as a decided fact 
that in all Pycnogonida the embryonal legs are quite thrown off during the second 
larval stage, and that they are in no way identical with the later imaginal fore 
limbs, the palps and the ovigerous legs, which latter also, andsohthissthererismo 
doubt, arise, although on the same metameres, still in other parts of these meta- 
meres. The two genera mentioned here, Pa//ene and Pseudopallene, also show that even if greater 
or smaller rudiments of the embryonal legs are found in the first larval stage, these rudiments have 
quite disappeared in the second stage, so that here no trace of limbs is found, from which a new 
development might arise. 
The second larval stage of Phoxichilidium shows, in accordance with the parasitical habits of 
the animal, a quite particular development. I have myself only had the first stage for examination; 
but as this larva has repeatedly been the object of thorough examinations, I may nevertheless, relying 
on these examinations, give a short survey of the development of its second stage, founded on the 
representation by G. Adlerz, Bidrag till Pantop. Morphol. 1888, especially referring to his figures 
4—12 in the two accompanying plates. The second larval stage then begins with the disappearing 
of both pairs of embryonal legs, so that only slight traces or remnants are left. After a couple of 
moultings, during which the rudimentary remnants of the legs by and by quite disappear, the imagin- 
al limbs are begun, in the common way and in the common order, without, however, breaking 
through the outer, common, wrapping membrane, until all the traces of the embryonal legs have dis- 
appeared. Adlerz now supposes the foremost pair of imaginal fore limbs (II) i.e. the palps, to be 
begun, cp. his fig. 10, upon which follows the further development of this pair of limbs in fig. 11 and 
fig. 4 (pl. I); but in the first place the genus Phoxichilidiwnm as imago has upon the whole no palps 
(only the ovigerous legs are found in the male), and next both pairs of fore limbs arise from the 
lower side of the animal in the way common in Arthropoda, by the growth of a little cellular mass, 
while Adlerz makes the extremity II develop as the other limbs of the Pycnogonida, especially the 
ambulatory legs, by a swelling of the sides of the blastoderm or the ectoderm. According to this I 
cannot take the small tubercles (II) on the side of the trunk to be the future ovigerous legs. Neither 
can I have any great confidence in the representation or interpretation by Adlerz of the ganglionic 
string in Phoxrichilidium, cp. his fig. 4, pl.I; at all events, it does not agree well with his figure of 
the same string in Wymphon Stroemii, which latter figure I take to be correct. In my opinion the 
ganglion ug which he interprets as «undre svælggangliet» (the nether pharyngeal ganglion), and from 
which a nerve is seen to branch off to the extremity II (it ought to be extr. III, as the former extre- 
mity is wanting in all Phoxichilidia), must be the ganglion from the first segment of the trunk plus 
the coalesced ganglia from the metameres of the embryonal legs, or, as it might also be called, the 
nethermost pharyngeal ganglion. Accordingly I think that after the description of this larva by Adlerz 
is neither here to be found any continuity between the second pair of embryonal legs and the ovige- 
rous legs of the male. 
Semper, Pycnog. und Larvenf. 1874, who, like Adlerz, takes it to be the second extremity 
(2), i. e. the palps, which grows to a little protuberance (beyond which, for the rest, it never passes) 
seeks to remove the difficulties by identifying the first pair of ambulatory legs with the compietely 
