The question of the age of the Northern Schist Range of Trinidad, or the Caribbean group of Messrs. Wall and Sawkins, is an important one in Antillean geology. Wall and Sawkins 3 state that “Calcareous rocks are represented by two varieties in this series, viz., crystalline limestones contained in the slates and alternating with them; and compact limestones, either quite unconnected with the schistose group, or only associated with its upper strata”. Further “The compact limestones form a portion of the LaventiUe Hills, and several islands of the gulf. Some beds to the east, situated at the base of the range, such as those of Laurel Hill, and inter-stratified in the slates, are supposed to belong to this variety; but the sections in general are not such as to indicate the precise relations of the compact limestones to the micaceous series”.