612 ON ARCTOCEBUS CALABARENSIS 
In his recently published “ Revision of the Species of Lemuroid 
Animals ” (Proc. Zool. Soc. 1863, p. 129), Dr. J. E. Gray has separated 
the Angwantibo from Perodcticus, and has made it the type of a new 
genus, dretocebus. The genera Perodicticus and <Arctocebus are 
differentiated as follows (2 ¢. p. 150) :— 
“tt The hand broad, the index finger abortive, clawless ; eyes 
moderate. Perodicticina. 
“15. PERODICTICUS, Bennett. 
“Tail shorter than the body. The hands and feet large. Fingers 
and toes free at the ends; the index finger rudimentary, but distinct. 
Lower cutting teeth large and prominent, and projecting. The apices 
of the vertebrae of the back, neck, and withers projecting beyond the 
skin, like prickles. 
“16, ARCTOCEBUS. 
“Tail very short. Hands and feet small, with the lower phalanges 
(not including the thumb) united in the skin, the two upper joints 
free ; the index finger abortive, reduced to a tubercle. Lower cutting 
teeth small, hyaline, hidden by the lips.” 
Leaving the skeleton (the characters of which I propose to discuss 
on a future occasion) out of consideration, the facts which I have 
brought forward in the present communication appear to me to 
justify, though on grounds different from those stated by Dr. Gray, 
the establishment of the new genus Arctocebus for the Angwantibo. 
This genus is distinguished from all other Lemuride by the com- 
bination of the following characters :— 
The tail rudimentary. The pinna of the ear has two projecting 
shelf-like lamellae above the auditory meatus. The index finger 
is rudimentary and nailless. The dental formula—z. =; «=; 
I—1? 
pm. >=; m.=. The anterior upper molars have eliere ridges 
and are = quacouspid the last is tricuspid. The last lower fae 
quinquecuspid. 
In Perodicticus, on the other hand, the tail is distinct, though 
short. The pinna of the ear has only one complete shelf-like 
lamella. The index finger is rudimentary and nailless. The dental 
formula is—z. 7; ¢. =; pm. ; m.2=. The anterior upper molars 
have oblique ridges and are quadricuspid, the last is bicuspid. The 
last lower molar is without a fifth cusp. 
END OF VOL. I 
