In the collections of the Leyden Geological Museum is a set of fossiliferous clay-stones which was long ago collected by the mining engineer Hulshoff-Pol in the coal quarries of Batoe Panggal 1), Eastern Borneo. He presented the collection in 1902 to Dr M. Schmidt, who at that time was making geological investigations in Borneo. After Dr Schmidt’s appointment to a professorship in Stuttgart, the fossil collections made by him in Borneo were acquired by the Leyden Geological Museum (1920). Fig. 1 roughly indicates the locality of Batoe Panggal, while Fig. 2 depicts the delta area of the Mahakkam or Koetei river and its neighbouring areas. The dotted area is again represented in Fig. 3 below.