Zoological Sociely. 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 fetus from spirits. 
II. Brapyrus. ?Acheus pars, F'. Cuvier, Dent. Mamm. t. 78 ; 
Guérin. Bradypus pars, Linn. Bradypus, Iiliger. 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 skuil 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. tridactylus, Linn. Am. Acad. i. 487 ; Syst. Nat. ; Shaw, Mus. 
Lever.t.3; Nat. Misc. t. 5; Griffith, A. K.v. t. 135. 
B. tridactylus, var. c. Desm. Mamm. 
2B. variegatus, Schinz. Cuvier, Thierre, iv. 510”? 
B. torquatus, I/liger, Prod. 109; ‘* Temm. Ann. Gen. Sci. Phys. 
vi. 212. t.91;” Fischer, Syn. Mamm.; Geoff. Ann. Mus. 
Acheus torquatus, “ Geoff.” Guérin, Iconog. R. A. t. 33.f.1 & 1a, 
skulls. 
B. cristatus, “‘ Temm. MSS.” fide H. Smith, Griff. A. K. iv. 271. 
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. 372. 
Ai sive Ignarus, Marcgrave, Brazil, 221. fig. cop. Clustus, 372. 
Hab. British Guiana ; Schomburgh. 
15* 
