DESCRIPTION OF FEONTISPIECE. 



FIG. 



1. The Gorilla {Troglodytes Gorilla). 



2. Skull of the Gorilla vertically and antero-posteriorly 



bisected, to show the great sagittal crest (s) rising 

 above the brain cavity, and the snpra- orbital crest (o) 

 above the orbit. 



3. The Squirrel Monkey (Chrysothrix sciurea). 



4. The Potto (Perodidicus Potto), showing the rudimentary 



condition of the index finger. 



5. The Angwantibo (Arctocebus calabarensis). 



6. The Tarsier (Tarsius spectrum), showing the foot at its 



maximum of elongation, relatively, in the whole order 

 Primates. 



7. The Aye-Aye (Cheiromys madagascariensis). 



