1897.] On the Affinities of Tarsius : 681 
of Lemuroidea I am unable to discover. The form of the uterus 
exhibits considerable variation in the Lemurs. Milne-Edwards 
says: “ L’Uterus des Indrisines a la forme d’une poche median 
dont le fond est bicorne les deux lobes ainsi constitués sont tres 
peu saillants chez les Propithiques et les Avahis, ils le sont 
davantage chez l’Indris.” In Propithecus especially, the cornua 
are extremely reduced, and externally the uterus has the ap- 
pearance of the uterus simplex of the Anthropoids. In the 
gravid uterus, owing to the extremely small size of the cornua, 
the single fcetus occupies one horn and all the body of the 
uterus; in Lemur the non-gravid cornua is occupied as shown 
by Turner by a prolongation of the chorion. It is not difficult 
to imagine the derivation of the uterus of the Apes from the 
condition found in the higher Lemurs, further constriction of 
the fallopian tubes of Propithecus and obliteration of the slight 
septum dividing the rudimentary cornua of this genus would 
produce the pure type of uterus simplex found in the Apes. 
I will now pass on to consider the paleontological history 
of the Primates and the conclusion which may be drawn from 
it. Prof. Hubrecht claims that throughout the whole Tertiary 
period the Lemurs and Apes were perfectly distinct, and, more- 
over, he concludes that we must go as far back asthe Mesozoic 
to find the two stem forms of these suborders. I hold there is 
absolutely no paleontological evidence to support this deduc- 
tion, and all our knowledge of the fossil Primates show that 
the Apes have arisen later than the Lemurs. Prof. Hubrecht, 
following Ameghino, refers the Santa Cruz formation, in which 
Homunculus occurs, to the Eocene. All paleontologists now 
admit that the Santa Cruz beds are of much later date than 
the Eocene, and it appears probable that they are not earlier 
than the Lower Miocene. If there is anything in the biologi- 
cal law that less specialized forms originate earlier than the 
more modernized types, it is surely applicable to the Primates 
where every one must acknowledge that an Ape is a much 
more highly differentiated organism than a Lemur. 
I will not consider the so-called Primates from the lower- 
most Eocene, Puerco. We know little about these forms, but, 
as far as our knowledge goes, such genera as Indrodon and 
