MAMMALIA— QUADKUM AN A.

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proportion to the body, the latter being slender, and its fur intensely black.These characters, which are scarcely rediscoverable in stuffed specimens,would not withhold me from persisting in the union of A. ater and paniscus,did not our author subjoin to them the statement that the young in theformer species are black at their birth, but in the latter, on the contrary, ofa dirty olive green tint. According to a specimen preserved in spirits of wine,in which the thumb was wanting to the right, but present on the leftfore-hand, I had united A. paniscus and pentadactylus into one species, aproceeding the validity of which is not admitted by Tschudi, seeing that bothhad different circuits of distribution, and that he had never met with a casesimilar to mine; he therefore advances the conjecture that the specimen inquestion might have lost one thumb by an injury. Now this is certainly notthe case, as is proved by inspecting the right fore-hand, when the pollicialdeficiency is seen to have been congenital. Yet at present I would not layso much stress as heretofore upon this circumstance, since I learn fromTschudi’s account that both the species of Spider-Monkeys occupy verydifferent kinds of range, a fact that had also been previously told to me byNatterer, who met, indeed, on his travels, with A. paniscus, but never withA. pentadactylus.

Like the Reporter, Tschudi distinguishes only two species of Lagothrixbut interprets differently their synonymy. The L. cana, Geoffr., is regardedby Tschudi, after a comparison with the Parisian specimen, as not identicalwith the Gastrimargus olivaceus , Sp., but with the latter’s G. infumatus. Ifthis view be correct, then both the name as well as the description given byGeoffroy and Dcsmarest of their L. cana is thoroughly incorrect, since L.infumata has an entirely different colour. In order that no confusion mightbe caused to interrupt the definite settling of these doubts, I retain for thelatter species the name given it by Spix, while his Gastrimargus olivaceus is,without hesitation, to be denoted as L. Humboldtii, just as Tschudi de-scribes it.

The same traveller establishes three species of Howling Monkeys , fromPeru ; viz. Mycetes stramineus, rufimanus, and flavicaudatus. These threespecies I had blended with the Caraya, by reason of their being collectivelyvery imperfectly known, and only through the medium of isolated indivi-duals. But after learning from Natterer that he had never seen a specimenin the whole of Brazil which would agree with the M. stramineus mounted inour collection, I have since regarded it as the representative of a distinctspecies. From Natterer I likewise learnt that the M. rufimanus hithertoknown only by one specimen, had been frequently seen by him in troops,and that the female and young are not yellow like the Caraya, but coal-blacklike the male. Hereupon I saw myself necessitated to establish M.rufimanus also as a species per se. Again Tschudi expresses himself in