JULY 2, 1897. ] 
that he is on less stable ground than the pale- 
ontologist who, for example, in the case of the 
horse has dug up the actual tree out of the succes- 
sive Tertiary strata. Ontogenetic development 
undoubtedly makes us acquainted with czno- 
genetic variations which have been the cause of 
many a premature conclusion. In Tarsius, how- 
ever, it was not to any changes, hypothet- 
ical or otherwise, that attention was directed by 
me, but on the contrary to a persistence of a 
most unexpected agreement which reveals itself 
in the numerous details of a complicated ar- 
rangement, such as is only found in man, the 
monkeys (as far as investigated) and Tarsius. 
And whoever calls attention, as Mr. Earle does, 
to the liability of embryological structures to 
vary must necessarily recognize the high value 
of those cases in which there is evidence not of 
variation, but of stability. It is because of this 
stability that Tarsius should be placed some- 
where between (though not, of course, in the 
direct line) the Anthropoids and their unknown 
Mesozoic ancestors with a non-diffuse placenta- 
tion. 
Mr. Earle’s assumption that the diffuse stage 
of placentation of some of the Anthropoids is 
apparently directly comparable to that of the 
Lemurs is invalidated by recent researches on 
early human plastocysts, researches which all 
tend to confirm the objections against such com- 
parison which were raised by me in 1889 
(Quar. Journ. of Micr. Science, Vol. 30, p. 364 
and p. 382). 
Finally, Mr. Earle’s contention ‘‘ that it has 
not been shown as yet that the placenta in the 
lemurs is not a derivative of the chorion, as in 
the apes,’’ although perfectly justified when it 
was written, is nevertheless unsupported by the 
actual facts. 
Since Milne-Edwards has emitted the opinion 
which Mr. Earle cites in a footnote, the Le- 
murine placentation has been again described 
in the Quart. Journ. of Micr. Science, Vol. 36, 
p. 90, pl. 9-12. In addition to that I may now 
state, on the strength of observations as yet un- 
published, thatin a true Lemur, such as Nycti- 
cebus, the fusion of the vascular walls of the 
allantois with the non-vascular diplotrophoblast 
can be followed step by step. It is a totally 
different process from that by which the vascu- 
SCIENCE. 
ol 
lar chorion of man, monkey and Tarsius comes 
into existence. 
Another important point of difference between 
Lemurs and Tarsius which I have only lately 
been able to establish, thanks to tae prepara- 
tions just alluded to, is the presence in Nycti- 
cebus of a typical proamnion, so common 
among the lower Placental Mammalia and 
wholly absent in Tarsius and in man. 
A. A, W. HUBRECHT. 
UTRECHT, May 18, 1897. 
A CLAMP FOR FRAGILE GLASSWARE. 
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CARL BARUS. 
BROWN UNIVERSITY, PROVIDENCE. 
* The clamp can be obtained from Eimer & Amend, 
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