Vol. 40, No. 2 April 1999

Vervaecke, H.; Van Elsacker, L.; Möhle, U.; Heistermann, M.; Verheyen, R. F.: Inter-menstrual Intervals in Captive Bonobos ( Pan paniscus )..........283 Key Words: Inter-menstrual intervals; Pan paniscus ; Pan troglodytes.

Kato, Eiko: Effects of Age, Dominance, and Seasonal Changes on Proximity Relationships in Female Japanese Macaques ( Macaca fuscata ) in a Free-ranging Group at Katsuyama..........291 Key Words: Age; Dominance; Seasonal changes; Female Japanese macaques; Proximity relationships.

Schmittbuhl, Matthieu; Le Minor, Jean-Marie; Schaaf, Andre: Relative Orbitonasal Overlap in African Great Apes and Humans Quantified by the Automatic Determination of Horizontal and Vertical Lines of Reference..........301 Key Words: Hominoids; Face; Orbital opening; Nasal opening; Image analysis.

Caton, Judith M.: Digestive Strategy of the Asian Colobine Genus Trachypithecus..........311 Key Words: Colobinae; Trachypithecus spp,; Gasto-colic fermentation; Forestomach; Colon.

Sousa, M. B. C.; Peregrino, H. P. A.; Cirne, M. F. C.; Mota, M. T. S.: Reproductive Patterns and Birth Seasonality in a South-American Breeding Colony of Common Marmosets, Callithrix jacchus..........327 Key Words: Breeding colony; Birth seasonality; Callithrix jacchus ; Interbirth intervals; Long-term studies.

Arcadi, Adam Clark; Wrangham, Richard W.: Infanticide in Chimpanzees: Review of Cases and a New Within-group Observation from the Kanyawara Study Group in Kibale National Park..........337 Key Words: Chimpanzee; Infanticide; Cooperation; Sexual selection; Kanyawara.

Moreira, Miguel Angelo Martins; Seuánez, Héctor N.: Mitochondrial Pseudogenes and Phyletic Relationships of Cebuella and Callithrix (Platyrrhini, Primates)..........353 Key Words: Callitrichinae; Mitochondrial DNA; Cytochrome b ; Pseudogenes; Cebuella.

Mori, Akio; Iwamoto, Toshitaka; Mori, Umeyo; Bekele, Afework: Sociological and Demographic Characteristics of a Recently Found Arsi Gelada Population in Ethiopia..........365 Key Words: Gelada baboons; Demography; Population; Social change.

Remis, Melissa J.: Tree Structure and Sex Differences in Arboreality Among Western Lowland Gorillas ( Gorilla gorilla gorilla ) at Bai Hokou, Central African Republic..........383 Key Words: Positional behavior; Diet; Sex differencies; Fruit availability.

Johnson, Christine M.; Frank, Rebecca E.; Flynn, Danielle: Peering in Mature, Captive Bonobos ( Pan paniscus )..........397 Key Words: Pan paniscus ; Peering; Social behavior; Female status.

Research Report

Yoshihiro, Shinichi; Ohtake, Masaru; Matsubara, Hajime; Zamma, Koichiro; Han'ya, Goro; Tanimura, Yasuaki; Kubota, Hiroyuki; Kubo, Ritsuko; Arakane, Atsuhiro; Hirata, Toru; Furukawa, Mari; Sato, Aki; Takahata, Yukio: Vertical Distribution of Wild Yakushima Macaques ( Macaca fuscata yakui ) in the Western Area of Yakushima Island, Japan: Preliminary Report..........409 Key Words: Macaca fuscata yakui ; Vertical distribution; Troop density; Troop size.