1897,] On the Affinities of Tarsius : 683 
closely resembles that of the Jndrisinx, whereas, in the other 
Cebide, the upper back teeth are transitional in structure, be- 
tween the tri- and quadritubercular types, and the cusps are 
bunoid. The molar pattern of recent Lemurs and Old World 
Apes is fundamentally different, but they may be brought into 
closer relations by means of the primitive structure of the 
molars of Tursius or Anaptomorphus. If Tarsius stands near 
the common ancestor of both Apes and Lemurs, then we must 
suppose that the teeth of the two phyla of recent Primates have 
increased in complexity during geological time. Nevertheless, 
in the Anthropoid Apes the molar pattern shows plainly a 
process of degeneration from a higher type, more like that 
found in the Cercopithecidex. 
Until recently no known Primate, fossil or recent, possessed 
a closed orbit as in the Apes and proclivous incisors and cani- 
niform first lower premolar as in the Lemurs. This combina- 
tion of characters is found in the Malagasy fossil lately de- 
scribed by Forsyth Major under the name of Nesopithecus. The 
skull, as far as known in Nesopithecus, is broad and short like ` 
that of the Apes, and as in the latter group the lachrymal fora- 
men is within the orbit. Again, the structure of the true 
molars is exactly like that of the Anthropoids. On the other 
hand the form of the premolars is more like that of the Lemurs, 
and, as far as I can learn from Major’s figures, all the upper 
premolars have small internal lobes. The incisors of Nesopi- 
thecus are not preserved, but from the oblique position of their 
alveolii Major concludes that these teeth must have been hori- 
zontal as in the living Lemurs. Moreover, as in the latter 
group, the first lower premolar functions as a canine. The 
collection of characters occurring in Nesopithecus completely 
breaks down the differential characters of the skeleton which 
is usually given as separating the Lemurs from the Apes. 
Either these two groups should be united, or Nesopithecus must 
be placed in a new suborder of the Primates. It remains now 
to consider whether Nesopithecus clears up the problem of the 
relation of the Lemurs to the Apes. Lydekker is of the opin- 
ion that Nesopithecus is a form closely related to the stem type 
which gave origin to both Lemurs and Apes. For my part, I 
