96 A. A. W. HUBRECHT. 
being non-vascular. The exact terms of Milne Edwards are 
the following (1. ¢., p. 283) :—** Les parois de l’allantoide sont 
délicates et transparentes, aucun vaisseau ne s’y distribue. Si 
Von injecte un liquide coloré dans le pédoncule de cette enve- 
loppe membraneuse on peut le suivre dans l’ouraque, & travers 
le cordon ombilical, jusque dans la vessie urinaire; preuve 
manifeste que cette poche, malgré ses caractéres anormaux, 
représente exactement l’allantoide des autres mammiféres.” 
The above description would suggest that in the Mada- 
gascar lemurs the allantois plays a part which is to a certain 
extent comparable to what Selenka! has described for Di- 
delphia (l. ¢., pl. 16, figs. 1—5, pls. 17,18). But then in 
Didelphia it is the yolk circulation by which the chorion is 
vascularised, whereas in Milne Edwards’ lemur fcetus he 
finds the umbilical vesicle to be extremely reduced. ‘Traces of 
it can only be made out in embryos of very early develop- 
mental stages. 
This latter fact shows that a comparison with the Didelphia 
does not carry us very far. The vascularisation of the chorion 
of the Madagascar lemurs must be a phenomenon sui ge- 
neris if Milne Edwards’ observations are confirmed; and it 
will be understood that for this reason an exact insight into 
the state of affairs as they present themselves in Nycticebus 
is all the more desirable, especially if all the genetic stages be 
closely followed, as the now available material promises to 
admit of. 
This will at the same time explain why I wish to refrain 
from further discussing the point on this occasion. 
Still I may be allowed to refer to an earlier publication in 
which I have insisted on the advisability of restricting the use 
in mammalian embryology of the name chorion.” I have there 
argued at some length why I proposed ‘‘ henceforth to restrict 
the use of the term chorion to man, and—dependent upon 
1 *Studien z. Entwickelungsgeschichte der Thiere,’ Heft 4, “ Das 
Opossum,” p. 136. 
2 «The Placentation of Hrinaceus europeus, &.,” ‘Quart. Journ. 
Micr. Sci.,’ vol. xxx, 1889, p. 382. 
