NO. 5 MAMMALS OF PANAMA GOLDMAN 59 



Family CHOLOEPODIDAE. Two-toed Sloths 



The two-toed sloths, family Choloepodidae, are similar in habits to 

 the three-toed sloths, family Bradypodidae, but differ notably in 

 details of structure. The number of digits and claws on the fore 

 limbs is reduced to two. The pelage of the top of the head is inclined 

 backward and there is no frontal ruff. The anterior teeth in both 

 jaws are greatly developed, exceedingly sharp, triangular and canine- 

 like, and shearing together exclusively, present a condition very 

 different from that exhibited by the Bradypodidae. The anterior 

 nares are broad and low. The nasals, laterally expanded between 

 the orbits, articulate with the lachrymals. The audital bullae are 

 reduced to bony rings. The angle of the mandible is very short and 

 the condyle considerably extended transversely. 



Genus CHOLOEPUS Illiger. Two-toed Sloths 

 The recognition marks of the genus are the same as those of the 

 family. 



CHOLOEPUS HOFFMANNI Peters 

 Hoffmann's Two-toed Sloth; Perico Lijero 



Choloepus hoffmanni Peters, Monatsber. k. preuss. Akad. Wissensch. Berlin, 

 1858, p. 128. Type from Costa Rica. 



Hoffmann's sloth, originally described from Costa Rica, apparently 

 ranges throughout Panama where it is the only member of the family 

 with the digits and claws of the fore foot reduced to two in number. 

 Specimens from Panama are apparently typical; like those from 

 Costa Rica they exhibit varying intensity of the brownish tone of the 

 underfur. The greenish outer color of the long hairs is now known 

 to be due to the presence of small green algae (Alston, 1879, P- I ^3), 

 which assist materially in rendering the animal inconspicuous, espe- 

 cially when among masses of epiphytic vegetation. 



Under the name Choloepus didactylus, Sclater (1856, p. 139) notes 

 the collection of the species by Mr. Bridges in western Panama as 

 follows : " From the vicinity of David. I believe neither this Sloth 

 nor the Little Anteater has been hitherto observed so far north." 



These sloths are rather common in the northern end of the Canal 

 Zone where they were usually seen curled up in a ball in the extreme 

 top of some rather tall tree. They commonly choose a fork in which 

 to rest, with their heads upward and the long hooked limbs clasping 

 the main trunk. When shot they often strike out frantically with 

 their long arms, and after a moment slowly loosen their hold and 

 drop crashing to the ground. One was found feeding early in the 



