ZOOLOGY. 311
locality, in order to meet with all the different kinds. I sub- join a list of the species, with the localities in which they were found.
MONKEYS FOUND ON THE AMAZON AND THE RIO NEGRO.
i. Mycetes seniculus, Geoff. ; on the Rio Negro and the north bank of the Amazon.
2. Mycetes caraya, Gray ; on the Upper Amazon
3. Mycetes beelzebub, Br. Mus. ; Para.
4. Lagothrix Humboldtii, Geoff. ; Upper Amazon and west of Rio Negro.
5. Ateles paniscus, Geoff. ; Guiana, north bank of Amazon and east of Rio Negro.
6. Cclnis apella, Erxk (?) ; Amazon and Rio Negro.
7. Ccbus gracilis, Spix ; Rio Negro and Upper Amazon.
8. Callithrix sciureus, Geoff. ; the whole Amazon valley.
9. Callithrix torquatus (amidus, Geoff.) ; Upper Rio Negro.
10. Callithrix personalis, Geoff. ; south bank of Upper Amazon.
11. Nyctipithecus trivirgatus, Humb. ; Upper Rio Negro.
12. Nyctipithecus felinus, Spix ; Upper Amazon.
13. Pithecia irrorata (hirsula, Spix) ; south bank of Upper Amazon.
14. Pithecia , north of Upper Amazon.
15. Brachiurus satanas, Br. Mus.; Guiana, east bank of Rio Negro.
16. Brachiurus oakary, Spix ; Upper Rio Negro.
17. Brachiurus rubicundus, Isid. ; Upper Amazon.
18. Brachiurus , south side of Upper Amazon.
19. Jacchus bicolor, Spix; north of the Amazon and Rio Negro.
20. Jacchus tamarin, Br. Mus. ; Para.
21. Jacchus n.s., Upper Rio Negro.
Of the above, the first seven have prehensile tails, a character only found among the monkeys of America. The howlers, forming the genus Mycetes, are the largest and most powerful. They have a bony vessel situated beneath the chin, and a strong muscular apparatus in the throat, which assists in producing the loud rolling noise from which they derive their name, and
