1897.] On the Affinities of Tarsius : 571 
ciated the essentially lemurine characters of Tarsius, and which 
I should like to emphasize, do not occur in any other Mam- 
malian group except in the Lemurs, is evident from his paper. 
Hubrecht, who has recently written an important paper on 
the placentation of Tarsius insists on the close relationship be- 
tween this genus and the Apes. Because Hubrecht finds that 
the histological structure of the placenta and the stalk con- 
necting it with the embryo in Tarsius is structurally like that 
of the Anthropoids, he proposes to overthrow our present sys- 
tem of classification of the Primates, dividing this group into 
two distinct orders, and placing Tarsius, also the fossil genus 
Anaptomorphus, among the Apes. I believe that Hubrecht, in 
his discussion of the systematic position of Tarsius, has not 
taken into consideration the whole organization of this genus, 
and furthermore I am of the opinion that any classification of 
the Mammalia depending solely on the structure of the pla- 
centa and its connections will prove to be unreliable. 
I am aware that there are many difficulties in the way of 
claiming that Lemurs and Apes are genetically related, but if 
one eliminates some of the highly adaptive and specialized 
` characters of the Lemurs, which appeared late in their evolu- 
tion, then these two groups of Mammals approach each other 
very closely and on osteological characters alone, we are un- 
able at present to surely separate the early Lemurs from the 
Apes. In other words, the extinct Lemurs possess certain 
characters which are now found widely separate in the two 
suborders of recent Primates. 
In order to allow the reader to form an unbiased opinion of 
the affinities of Tarsius, I will briefly review Hubrecht’s im- 
portant contribution to the placentation of Tarsius, and follow 
him in his comparison of the placental connections ef Tarsius 
with that of Erinaceus, a typical Insectivore, and also compare 
both with what is known of the placentation in the true 
Lemurs. 
In the early as in the later stages of Tarsius, the yolk sac 
only takes up a small portion of the cavity of the blastocyst, 
and there is never present an omphaloide placentation as in ~ 
Erinaceus. In this character of its development Tarsius 
strictly follows the plan of the Anthropoids. 
