Zoological Society. 227 



The hinder angle of the lower jaw of the two skulls, the one of a 

 young and the other of an adult animal, in the Museum collection, is 

 nearly similar in form. The condyloid process of the young is short 

 and truncated behind, that in the older jaw being produced and bent 

 back at the tip. 



In the British Museum collection there are five skins of adults, two 

 very young, one dry, the other in spirits, and three skulls more or 

 less perfect. 



The very young specimen in spirits in the British Museum is figured 

 in Griffith's Animal Kingdom, and Seba figures the foetus from spirits. 



II. Bradypus. ? Acheus pars, F. Cuvier, Dent. Mamm. t. 78 ; 

 Guerin. Bradypus pars, Linn. Bradypus, Illiger. Tardigradus, sp. 

 Brisson. Arctopithecus, Gesner. 



Hands and feet three-clawed. Skull flattened above on the fore- 

 head. Grinders : front upper small, cylindrical ; front lower small, 

 transverse, compressed. Intermaxillary bones none, or very rudi- 

 mentary. The upper process of the zygomatic arch with a broad 

 process in front, forming a back edge to the orbit. Pterygoids sepa- 

 rate, much-swollen and raised, very thin, enclosing a large vesicular 

 cavity. 



Lower jaw produced in front between the teeth, flattened. 



Cuvier, Oss. Foss. v. 88, described the skull of this subgenus. 



Blainville (Osteograph. Bradypus, t. 3) figured an imperfect skull 

 of a young animal under the name of B. torquatus, but it does not 

 show the characters of the pterygoid process, and it has no appear- 

 ance of the anterior process on the upper part of the zygomatic arch 

 forming the upper hinder part of the orbit, which is found in most 

 of the skulls of this genus. This skull may be the one described by 

 Cuvier, as M. Blainville observes that the skull he figures formed 

 part of the old collection, and was taken from a skin collected in 

 Brazil by M. Delalande. 



1. Bradypus crinitus. 



Greyish, sides reddish ; back of the neck with a mane formed of 

 elongated black hairs. 



B. crinitus, Browne, Jam. 489. 



B. tridactvlus, Linn. Am. Acad. i. 487 ; Syst. Nat. ; Shaw, Mus. 

 Lever t 3 {Nat. Misc. t 5 ; Griffith, A. K. v. t. 135. 



B. tndactylus, var. c. Desm. Mamm. 



? "B. variegatus, Schinz. Cuvier, Thierre, iv. 510"? 



B. torquatus, Illiger, Prod. 109; " Ternm. Ann. Gen. Sci. Phys. 

 vi. 212. t. 91 ;" Fischer, Syn. Mamm. ; Geoff. Ann. Mus. 



Acheus torquatus, " Geoff." Guerin, Iconog. R. A. t. 33. f. 1 & 1 a, 

 skulls. 



B. cristatus, " Temm. MSS" fide H. Smith, Griff. A. 



Ai a, collier, Cuvier, Oss. Foss. v. 88. 



Three-toed Sloth, Penn. Syn. t. 29 (from B.M.). 



Ignarus, Clusius, Exot. 110 fig. 372 fig. 



Unau, Laet. Amer. 618. f. 618. cop. Clusius fig. at p. 3/2. 



Ai sive Ignarus, Marcgrave, Brazil, 221. fig. cop. Clusius, 372. 



Hab. British Guiana ; Schomburgk. 



15* 



