134 THE VOYAGE OF H.M.S. CHALLENGER. 
with the wall of the leg. The one part is filled up with the ovary, the other partly with 
the ccecum of the intestine. The ovarian eggs are small and are furnished with a ~ 
central germinal vesicle. Most probably the females of the species of Ascorhynchus have 
an oviduct like that of the species of Colossendeis. The species of Pallene show the same 
disposition as in Nymphon. A transverse section of the thigh of Pallene australiensis 
corresponds perfectly with that of NMymphon breviccudatum, figured -in Plate XVI. _ 
fig. 7; there is one very large and probably mature egg with an eccentric germinal 
vesicle, and numerous smaller ovarian eggs, with their vesicle in the centre. Moreover, 
minute researches .on Pallene brevirostris (an inhabitant of the Dutch coast) admit of no 
doubt as to the structure of the ovaries; they are totally wanting in the body, and take 
their origin in the thighs of the legs. The eggs when mature are large, and their number 
is limited. 
In the genus Phowichilidium I studied the anatomy of the body of Phoxichilidium 
pilosum (as female specimen) without meeting with the ovary. In the legs of this 
species, however, and also of Phowichilidiwm patagonicum, I soon found it. The 
whole cavity of the leg is often filled up with eggs, and these are éven observed 
pressed closely against the wall of the leg (Pl. XVI. fig. 17). The eggs are comparatively 
small and very numerous. The membrane of the eggs is much thicker than is the case 
with the eggs of the other genera (Pl. XXI. fig. 18). Neither in the species of Padlene 
nor of Phoxichilidium did I observe the least trace of an oviduct, so I think that here, 
‘as in Nymphon, the genital aperture communicates directly with the cavity of the leg. 
I think also that the circumstance I often observed of eggs free in the cavity of the 
leg is in support of this opinion (Pl. XXI. fig. 18). For the other genera of Pyenogonids 
I have, so far as the ovaries are concerned, no observations worth mentioning. 
7. Observations on the Embryology of the Pycnogonida.—Among the Pycnogonids of 
the Challenger Expedition there were some species provided with eggs. On account of 
the great importance of embryology for the study of the affinities of a group of animals 
I tried to acquire as much information on this subject as possible. Unfortunately, with 
the exception of one species belonging to the genus Ascorhynchus, G. O. Sars, all the 
species with egg-masses belong to the genus Nymphon, Fabr., but of these there are out 
of twelve species no less than: six provided with eggs. 
The researches of Kroyer, Johnston, Goodsir, Dohrn, Semper, Cavanna, and eeeale 
have shown that in the geriera Pycnogonum, Pallene, Phoxichilus, Phoxichilidium, 
Nymphon, &c., the eggs after having been laid are carried on the so-called ovigerous 
legs. The honour of having discovered that not the females (as was believed by the 
older authors) but the males fulfil the duty of bearing these eggs is due to Cavanna; this 
observation has since been confirmed by the researches of Dohrn, Bohm, and myself.’ 
1 The observations of Cavanna were published in the year-1875. It is indeed strange to see that neither Wilson 
nor Miers have heard of this discovery. These authors, in their descriptions of new species, &c., are therefore almost 
constantly confounding the two sexes. - : 
