274 PROFESSOR OWEN ON THE EXTERNAL CHARACTERS 
are different. The essential distinction in the New-World Simie is their having three 
premolars, instead of two, on each side of both jaws: and in this respect they show their 
lower grade and nearer approach to the unguiculate Gyrencephala. The Oucstitis differ 
in wanting a true molar on each side of both jaws: m. 3 is undeveloped in these small 
and short-jawed Marmosets. The homological characters of the ‘‘ macheliéres”’ in 
Quadrumana are given in the subjoined formule :— 
Old-Word Simie, ‘ singes de l’ancien continent,” Cuv. . p. 2, m. =3 = 20; 
‘353 
New- World Simie, ‘‘ singes du nouveau continent,” Cuv. . p. 3, m. =3 = 24; 
Marmosets, ‘‘ Ouistitis,’Cuv. . . . EE POI: Ss. a P= 0! 
P 3—3 2—2 
Thus it is seen that the Ouistitis, instead of Sanne the Old-World Apes in denti- 
tion, differ from them in a greater degree than do the other New-World Simie: they 
have not only one premolar more, but one true molar less, in the dental formula. 
In their deciduous dentition the Marmosets correspond with the other American Qua- 
drumana'!. 
With regard to the character which Cuvier derived from the feeble and hardly oppo- ° 
sable anterior thumb in the Ouistitis, that great naturalist had remarked, in the same 
section of his classical work, that one of the ‘‘ Sapajous”’ (Mikiri) had a very short 
thumb; another (Chamek) had the thumb still shorter, wanting the ungual phalanx 
and nail; and a third (Coaiti*) had no thumb visible. About the same period Isi- 
dore Geoffroy St.-Hilaire had generalized the fact of the inferiority of the thumb of 
the anterior hand, in the Howlers (Mycetes), eeu (Cebus), and Caparos (Lago- 
thriz, Geoffr.) *. 
The characters of the extremities, therefore, like those of the teeth, in the Ouistitis, 
are invalidated, and their separation as a primary group of Quadrumana cannot be 
maintained. In my ‘Odontography ’ I adopted three primary groups of Quadrumana :— 
1. the Lemurids or Makis, including Cheiromys ; 2. the New-World Simi@ of Cuvier, 
‘ €Odontography,’ p. 439 (1840). The system of notation is there explained. See also ‘ Phil. Trans.’ 1850; 
and the article ‘‘ Teeth,” ‘Cyclopedia of Anatomy.’ Mr. Blyth remarks, “ We cannot but think that Cuvier 
has, in this rare instance, attached undue importance to the number of molar teeth, in so decidedly separating 
the Ouistitis from the other small American Quadrumana” (Orr’s edit. of the ‘Animal Kingdom,’ 8yo, 1840, 
p- 63). The determination of the kinds of teeth confirms the suspicion. 
> « Absolument sans pouce visible’? (Régne Animal, i. p.101). The metacarpal is present, but concealed by 
the skin. 
* « Hurleurs ou Alouates :—pouce antérieur de moitié moins long que le second doigt, trés-peu libre dans ses 
mouvemens, et 4 peine opposable. 
“ Sajous ou Sapajous proprement dits :—les pouces antérieurs sont peu allongés, peu libres dans leurs move- 
mens, et peu opposable aux autres doigts; absolument comme dans les Hurleurs et les Lagothriches”’ (Diction- 
naire Classique d’ Hist. Nat. t. xv. 1829). Mr, Ogilby, by independent observations, arrived at the same con- 
clusion as to the inferiority of the anterior thumbs in the ‘‘ New-World Simie”’ of Cuvier, and went so far, in 
his application of the character, as to sever them from the other Quadrumana of Cuvier, and associate them 
with the Opossums and Cheiromys, in an order called Pedimana (Proc. of the Zool. Soc. March 1836) ; “ Ob- 
servations on the Opposable Power of the Thumb in certain Mammals” (Mag. of Nat. Hist. vol. i. 1837, p. 449). 
