In the present paper, certain morphological features and the ontogenetical development of members of the subfamily Pseudorbitoidinae Rutten, 1935 are discussed. A study of the evolution of Pseudorbitoides Douvillé, 1922 resulted in testing the concept of nepionic reduction in populations of this genus from Jamaica (Green Island- and Sunderland Inlier) and Curaçao (Cas Abao Limestone lenses). Within the Pseudorbitoides-lineage, P. trechmanni pectinata subsp. nov. is distinguished from P. trechmanni trechmanni Douvillé on account of different post-juvenile features.