REPORT ON THE PYCNOGONIDA. . . 133 
appearance of being surrounded by a very thick and concentrically stratified membrane 
(ovarian egg of Nymphon brevicaudatwm, Pl. XXI. fig. 15). In other species (Vymphon 
robustum, Pl. XXI. fig. 16) this membrane is perfectly transparent, while in both cases 
the granular protoplasm of the egg within this thick membrane or capsule seems to be 
surrounded by its vitelline membrane. In a third case, which I observed in Nymphon 
longicoxa (Pl. XXI. fig. 17), the membrane of the egg does not seem to be thick, but 
nregularly folded and crumpled ; yelk-particles are here very numerous in the central part 
of the egg, which surrounds the germinal vesicle; and the protoplasm of the egg extends 
beyond this central part till it reaches the crumpled membrane. However, it is very 
probable that the condition of the eggs has suffered from their having been so long in 
alcohol, only I wish to point out that from what I observed it is almost certain ‘that 
any one studying the formation and the development of the animal egg, will find a very 
interesting object in the egg of the Pycnogonida. The dimensions of the mature ova 
are very different. Of the specimens I studied they are largest in Nymphon longicoxa, 
N. brevicaudatum, and N. robustum, a great deal smaller in N. brachyrhynchus and 
N. hamatum (the number of egos Ss in an egg-mass being always in inverse propor- 
tion to their size). 
While in the younger ovarian eggs the ata vesicles as a rule are placed in the 
centre of the egg, in the very large mature egg the vesicle is placed close to the wall. 
Sometimes (Mymphon longicoxa) it has the shape of a sand-glass, and once I observed an 
extremely small micropyle canal in the membrane of the egg, just opposite the place 
oecupied by the germinal vesicle. As a rule there i is only one germinal spot, but I once 
observed two distinct:spots in the germinal vesicle of the egg of Nymphon longicoxa. In 
the ovarian egg of Nymphon robustwm one distinct nucleolus may be observed almost 
exactly in the centre of the rounded and granular germinal spot. As for the manner 
in which the eggs make their way to the genital apertures in those casés in which no 
true oviduct is observed, I think there can be no doubt that the body-cavity itself per- 
forms the function of an oviduct. The absence of such a duct at the genital pores, 
and the fact that I repeatedly observed detached eggs pressed against the connective 
. tissue surrounding the ventral ganglia. or other parts in the interior of the body admits 
of no doubt in this respect. z 
All I have said about the ovary and the formation of the ova in the genus Nymphon 
also holds good in the case of the other genera. The limited quantity of specimens 
prevented me from making a section of the body of species of these genera. Most 
probably Ascorchynchus will show the same disposition as Colossendeis. A transverse 
section of the thigh of one of the legs of Ascorchynchus orthorhynchus is figured in 
Plate XVI. fig. 11. The thigh is much more dilated than one of the other joints of the 
leg, yet it is not round but flattened, and the contents are almost divided into two un- 
equal parts by the large chitinous thickening, which at the one side is in conhection 
