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Proceedings of the Boycd Society 
I have also recently obtained a female specimen of Myxine in which 
all the large eggs in the ovary had a slight projection at each end, 
and in these knobs the ends of the threads could he seen through 
the connective tissue. In these eggs the polar threads were half 
way or more towards their complete development. 
In January I obtained two or three other specimens in which the 
eggs were nearly as ripe, the projections formed by the development 
of the threads being visible, but not quite so prominent. In 
sections of the ripest eggs above described it is seen that the 
follicular epithelium at the poles of the egg has become greatly 
thickened, while the connective tissue layer has become thinner. 
The threads are contained in deep cylindrical sacs formed by the 
epithelium; the distal ends of these sacs project deeply into the 
connective tissue layer, which is very thin over their terminations. 
The epithelium is thick all round these sacs, and it is quite evident 
that the threads and the layer from which they project are formed 
by the epithelium. The micropyle in these ripest eggs is in the 
same condition as before, and is still closed by a thin layer of 
chorion at its inner end. I have not yet found the germinal vesicle 
in the eggs at this stage. The question whether a vitelline mem- 
brane exists internal to the chorion I have not yet decided. 
Development of the Ova . — The ovary of Myxine differs from that 
of other vertebrata, or craniata, in consisting of an extremely thin 
fold instead of a somewhat solid mass. It is impossible to define 
the boundary between ovary and mesoarium. The mesoarium 
extends the whole length of the body on the right side only (in two 
specimens I have found it developed on the left side only), and is 
attached at the angle between the mesentery and intestine. The 
eggs originate at the free edge of the ovary, which is only slightly 
thickened, and as they grow large pass inwards, the largest eggs 
being always nearest to the attached border of the mesoarium. 
There is no transition in thickness between the membranous meso- 
arium and the thick connective-tissue layer of the follicle, but the 
former passes abruptly into the latter. The line of attachment of 
the mesoarium passes round the longest circumference of the ellip- 
soidal follicle. When the eggs are large they stretch the meso- 
arium and hang down beyond the edge of the ovary, but the 
relations pointed out are never altered, not even when the egg 
