22 BRADYPUS. 
be separated. Teeth rather small, anterior tooth in the upper jaw 
smaller than the rest, and none projecting much beyond the others. 
Superior outline of skull greatly arched; nasals short, broad, pointed 
posteriorly; interpterygoid fossa very broad and deep; palate nar- 
rowed posteriorly; arch rounded. Cervical vertebre, nine; some- 
times the eighth, and always the ninth, bear short ribs. Windpipe 
folded on itself before reaching the lungs. Mamme two, pectoral. 
Fic. 5. BRADYPUS INFUSCATUS. 
No. 2824 Am. Mus. Nat. Hist. Coll. 3 nat. size. 
KEY ‘TO: THE SPECIES: 
A. Dorsal patch yellow with black central streak. PAGE 
a. Forehead, cheeks, and chin reddish brown. B. castaneiceps 22 
b. Forehead, cheeks, and chin dark brown..... B. infuscatus 23 
17. castaneiceps (Arctopithecus), Gray, Proc. Zoél. Soc., 1871, Pp. 444. 
CHESTNUT-HEADED SLotH. Camaleon in Nicaragua. 
Type locality. Chontales, Nicaragua. 
Geogr. Distr. Nicaragua, Central America. 
