At the end of November 1960, the Leiden Museum received an interesting collection of animals, mostly fishes, from the Niger delta. All specimens were collected by Mr. H. J. G. Beets, at the time employed by Shell B.P. — Delta Investigations, during the period May to August 1960, and in the region between Port Harcourt and Brass. Unfortunately, owing to lack of time, the separate specimens or lots were not labelled, but the collecting localities are limited in number and restricted to only the eastern part of the delta. The fish collection, consisting of 130 specimens, proved to belong to 51 species, some of which gave occasion for a reexamination and comparison of Bleeker and Steindachner types in the Leiden Museum collection. Collecting localities and descriptive notes (fig. 1) The following information is almost wholly taken from the extensive notes provided by Mr. Beets. Loc. I : Brass, Brass River, St. Nicholas River, Okpoma Creek, and small confluent creeks. In this area, situated immediately behind the Atlantic coast, the water must be considered brackish (Okpoma Creek) to almost completely salt. Most specimens were collected here. Loc. 2: Old Sangama, environs of Sego Creek, about 45 km WSW of Port Harcourt. Fresh water throughout the year. Only few fishes collected. Loc. 3 : Ekulama, Bille Creek, San Bartholomeo River, 35-45 km SW of Port Harcourt. Brackish water. Loc. 4 : Port Harcourt and environs. Brackish water. Behind the sandy beach and a narrow zone of coastal forest, a wide marshy area reaches far inland to the foothills, its average width being approximately 35-40 km. This whole zone is covered with mangrove forest, especially