1864.] PROF. HUXLEY ON ARCTOCEBUS CALABARENSIS, 325 
In Galago sennaarensis the inner posterior cusp of the last upper 
molar is obsolete ; but the fifth cusp of the last lower molar is well 
developed and ridge-like. In this species the lower molars might 
be said to be Tapiroid, the elevation which answers to the oblique 
ridge being shorter and less distinct, while the two transverse ridges 
connecting the outer and inner cusps are more obvious (fig. 5, D). 
Right molars and premolars of both jaws of Galago sennaarensis. 
A and C, upper; B and D, lower jaw. 
Galago maholi, also, has the inner posterior cusp of the last upper 
molar obsolete, and Tapiroid lower molars, the last of which is quin- 
quecuspid. 
Galago allenii has the inner posterior cusp of the third upper 
molar well developed; the lower molars are provided with an ob- 
lique ridge, nearly reaching the inner anterior cusp, while the third 
has a large fifth cusp. 
In Galago minor the inner posterior cusp of the third upper molar 
is obsolete ; the oblique ridges of the lower molars are tolerably well 
marked, and the last has a fifth cusp. 
Otolicnus garnettii and O. crassicaudatus have the inner posterior 
cusps of the third upper molars rudimentary, the oblique ridges of 
the lower molars but little developed, and the fifth cusp of the third 
lower molar rudimentary. 
The upper molar teeth of the ordinary Lemurs (Varecia, Lemur, 
and Prosimia, Gray) have the inner posterior cusp obsolete, or very 
small; and a very strongly developed cingulum, internally. The 
oblique ridges are sometimes present, sometimes obsolete. 
