PYCNOGONIDA. 23 
of the exeretory duct and thorn in contradistinction to Baranra Castell. Hoek, in Nouv. étud. 
Pycnog., 1881, draws the gland with excretory duct and thorn in Ammothea longipes, pl. XXX, 
fig. 40, and in Pycnogonum littorale, pl. XXX, fig. 45, as well as the gland alone in Wymphon gallicum, 
ping 4 2: 
The descriptions and figures of Dohrn, as well as most of those of Hoek do not very much 
resemble those given by me; but I suppose that they generally represent a younger stage in the 
development of the gland, whereas my figures, especially of the larva of Wymphon grossipes, pl. I, 
fig. 22, and those by Hoek of Wymphon longicoxa, Report Pycnog. «Challenger», pl. XX, fig. 5, which 
figures are very much alike, show the fully developed stage. 
Morgan, in Contrib. Embryol., 1891, has drawn the byssus-gland in the larva of 7anrystylum 
orbiculatum, pl. IV, fig. IX, in a shape most resembling my figure of the gland in Wymphon grossipes. 
Else Morgan does not mention the gland at all. 
I have been rather long in speaking of this gland, partly because it seems to me to have 
hitherto been somewhat overlooked, and partly because I suppose it to have some morphological, 
systematic importance, compared with the poison-gland in the corresponding pair of limbs in the 
Arachnida. Possibly it might also be compared with the gland which Dohrn has described by the 
name of «secretory organ», and which he mentions as occurring in the palps and the ovigerous legs, 
or, where these limbs are wanting, in the corresponding metameres. I think at all events this com- 
parison to be more obvious than the comparison with the sexual glands; comp. Dohrn, Pantop. Golf. 
Neap. 1881, his «Excretionsorgane» and the following paragraph, «Geschlechtsorgane und Entwickel- 
ung», p. 63 seg. 
fh hede relopmenorthersecomdlarvalstaselbesins withethesstrowimer os the 
hindmost'sesment'of the trunk, amd the separation ofaforemost ring-with the first 
pair of hind limbs, or ambulatory legs, upon which in a similar way the second and 
third pairs of ambulatory legs are separated, while the fourth pair and the caudal 
segment are seen behind as a three-cleft appendage. At the close of the development 
of this stage the embryonal legs have fallen off, but the imaginal limbs and fore- 
limbs, the palps and ovigerous legs, have not appeared, if they appear at all. Only 
very rarely the chelifori fall off already on this stage. The byssus-gland is kept till 
the development of the stage is finished. 
The development of the second stage does not take place at once, but through more or fewer 
castings of the skin, and in such a way, that sometimes a greater, sometimes a smaller interval is 
found between the origin and the development of each of these three pairs of ambulatory legs, while, 
however, the consecutive order is kept. Perhaps it may be called a little arbitrary to limit the second 
stage in the way we have done here, as in some species s0 great a pause may occur during the 
stage, especially after the development of the second pair of ambulatory legs, as is the case in Psew- 
dopallene circularis, that we might as well place the limit of a larval stage after the development of 
the second pair as after that of the third pair; in most Pycnogonid-larvæ, however, the development 
is evenly advancing, till the third pair of ambulatory legs have been developed. 
As in the preceding section the genera Pa/l/ene and Pseudopallene were especially mentioned 
