474 



THE CHANGING GENERATIONS 



tips, that suggest those of tree frogs. The nail of the first toe is small and 

 flattened, but the other nails are pointed and clawlike. The eyes are 

 immense, directed forward and almost touching above the small nose; 



they are enclosed in a complete 

 bony socket with flaring margins. 

 The sense of smell is much reduced; 

 tarsiers are insect feeders, and catch 

 their prey by sight, the great eyes 

 being adapted for night vision. The 

 teeth are much like those of lemurs 

 and insectivores. The brain is large, 

 the brain case rounded, and the face 

 reduced. The placental connections 

 with the uterus are concentrated 

 into a disk-shaped structure, which 

 is shed at birth as in the higher 

 primates. Although highly special- 

 ized in some features, in other 

 respects Tarsius is intermediate be- 

 tween the lemurs and the anthro- 

 poids. Primitive tarsioids occurred 

 with lemurs in the Paleocene and 

 Eocene epochs, and the higher 

 primates are believed to have come 

 from some early tarsioid line. 



The anthropoids. The remain- 

 ing primates form the suborder 

 Anthropoidea — the "manlike ani- 

 mals." They comprise the monkeys, 

 apes, and man, which share many 

 important characteristics. Com- 

 pared with lemurs and tarsioids 

 the anthropoids show numerous 

 advances. The brain is much larger 

 and more complicated. The eyes 

 are directed forward and have com- 

 plete bony sockets as in Tarsius, 

 but the tear ducts open within the 

 sockets instead of on the face. 

 Acuity of vision is increased by the 

 presence of the specialized "yellow spot" on the retina. The facial region 

 has been progressively reduced and the brain case expanded. The spinal 

 column is attached beneath instead of at the back of the skull, and the 



Fig. 29.3. A Philippine tarsier, Tarsius 

 species. (Photo by Isabelle deP. Hunt.) 



