The present paper consists of the revision of five species of fossil dipterocarpaceous woods, viz. Dipterocarpoxylon indicum, Shoreoxylon holdeni, S. mortandranse, S. megaporosum and Anisopteroxylon cuddalorense, described by Ramanujam (1956, 1960) from the Tertiary of South India, near Pondicherry, South Arcot district, Tamil Nadu (Madras). On re-investigation these were found very similar to the wood structure of the genus Dryobalanops Gaertn. f. and hence transferred to the genus DryobalanoxyIon Den Berger. The first species, i.e. Dipterocarpoxylon indicum, is renamed as Dryobalanoxylon indicum (Ramanujam) comb. nov., and the remaining four species, found identical with each other, are placed under Dryobalanoxylon holdeni (Ramanujam) comb. nov.

Nine species belonging to six dicotyledonous families have been described here from an assemblage of petrified woods collected from the Mio-Pliocene of Namsang beds near Deomali. They are Sterculioxylon varmahii sp. nov., Heritieroxylon arunachalensis gen. et sp. nov. of Sterculiaceae; Burseroxylon garugoides sp. nov. of Burseraceae; Mangiferoxylon assamicum Prakash & Tripathi of Anacardiaceae; Albizinium eolebbekianum Prakash and Millettioxylon palaeopulchra sp. nov. of Leguminosae; Lagerstroemioxylon deomaliensis sp. nov. of Lythraceae; and Laurinoxylon namsangensis sp. nov. and L. deomafiensis sp. nov. of Lauraceae. Modern comparable forms of these fossils still occur in and around the tropical evergreen to deciduous forests of Arunachal Pradesh, indicating the continuation of somewhat similar kind of vegetation and climatic conditions in this region from the Neogene to the present day.

Two fossil woods resembling those of Kingiodendron Harms and Bauhinia Linn. of the family Leguminosae are described from the Namsang beds (Mio-Pliocene) exposed along Namsang River at Deomali in Arunachal Pradesh. They have been named as Kingiodendron prepinnatum sp. nov. and Bauhinia deomalica sp. nov. respectively.

Fossil woods of Shorea, Holigarna, Cassia, Terminalia, Duabanga and Sideroxylon are described here from the Tertiary of Assam and NEFA. They were collected from the beds of Buri-Dehing River near Jaipur and Namsang River at Deomali. Most of the modern equivalents of these fossils are commonly found in the modern forests of Assam and NEFA indicating the occurrence of a somewhat similar type of forest in this region during the Tertiary (Mio-Pliocene) period.

Six species belonging to five dicotyledonous families have been described here from a collection of petrified woods made from the Tertiary (Mio-Pliocene) pyroclastic deposits of the basalt on the southern side of Canon in Blue Nile Valley. They are Mammeoxylon lanneoides Lemoigne emend. of Guttiferae, Cassinium ethiopicum sp. nov. of Leguminosae, Sapotoxylon multiporosum sp. nov. of Sapotaceae, Stereospermoxylon eoacuminatissimum gen. et sp. nov., S. grambasti sp. nov. of Bignoniaceae and Vitexoxylon africanum sp. nov. of Verbenaceae.