518 Opposable Power of the Thumb, 



which belong to them as Quadrumana and Pedimana respec- 

 tively, which may be easily traced between the constituent 

 members of each group, and which approximate them more 

 nearly to one another than to the analogous groups of the 

 other family. Thus, we have seen that the Didelphidae, though, 

 generally speaking, omnivorous, exhibit a marked predilection 

 for animal food. The very same appetites prevail among the 

 Simiadae, and that to an extent hitherto unsuspected by the 

 majority of zoologists, as is clearly demonstrated by the fol- 

 lowing extract from Baron Humboldt : — " La Viudita," says 

 M. de Humboldt, speaking of the Callithrix lugens, "seule 

 et abandonnee a elle-meme, devient furieuse a l'aspect d'un 

 oiseau ; elle s'elance sur lui comme un chat, et Pegorge a, l'in- 

 stant. Elle est tr^s-friande de viande fraiche, quoiqu'on la 

 nourrisse generalement de fruits; elle mange, commes les autres 

 Sagoins, en portant les deux mains a la fois a la bouche : a la 

 voir guetter les oiseaux et roder autour d'une cage, on la 

 prendrait pour un Mammifere carnassier du genre Viverra. 

 Je dois faire observer, cependant, ici, que ce gout pour une 

 nourriture animale ne se trouve pas uniquement chez le Dou- 

 roucouli et la Viudita, mais aussi chez des especes de Sagoins 

 qui sont connus depuis long-temps. Le Tamarin Negre de 

 Cayenne (Simia Midas Linn.) mange volontiers de la viande 

 cuite; et M. Audibert cite l'example d'un petit Sapajou, lequel 

 il a vu attraper des oiseaux sur les toits pour les devorer." * 



This is precisely what I have myself seen the Phalangers 

 and Petaurists do over and over again ; but there is a remark 

 incidentally made by Baron Humboldt in the foregoing pas- 

 sage, which indicates another relation between the Simiadae 

 and Didelphidae, and which deserves to be more particularly 

 noticed, as it depends, in some measure, upon the pedimanous 

 conformation of these animals. It is, that the Viudita, like the 

 other Sagoins, as M. de Humboldt observes, made use of both 

 its anterior members at the same time, for the purpose of 

 carrying its food to its mouth. This action, which I have 

 repeatedly witnessed both in the Simiadae and Didelphidae, 

 manifestly arises from the want of the opposable thumbs on 

 the anterior extremities, and the consequent impossibility of 

 grasping the object securely with one hand. I have never 

 observed any species of Simiae or Lemuridae to have recourse 

 to both hands under similar circumstances; obviously, because 

 the more perfect structure of their organs of prehension pre- 

 cludes the necessity of doing so, to which the less favourably 

 organised Pedimana are reduced : and this is a very important 

 fact, which not only indicates a new and intimate affinity 

 * Humb. Rech. d'Obs. Zool., i. 320. 



