The extant neolampadids are known from depths as great as 1,200 m (Neolampas), however, most specimens have been collected form depths ranging from 135-400 m.
When Kier (1966) erected the family Pliolampadidae he already realised that it was "not very homogeneous and may not represent a natural or phylogenetic grouping." The absence of a gonopore in genital plate 3 is unusual in Pliolampas and links that genus to Neolampas. Neolampadidae was erected by Lambert (1918) for small apetaloid individuals lacking phyllodes. Philip (1963) redefined the group as forms with all adapical plates single pored, raising it to ordinal status. Philip included a range of forms with diverse apical discs. Here we restrict Neolampadidae to just those cassiduloids with two or three gonopores (genital plate 3 lacking a gonopore), and place apetaloid forms in the subfamily Neolampadinae.
The Lower Cretaceous catopygid Pygolampas is superficially very similar to Pliolampas and Studeria but has pore-pairs below the petals.
Durham, J. W. & Wagner, C. D. 1966. Neolampadoids in Treatise on Invertebrate Paleontology, Part U Echinodermata 3. The Geological Society of America and The University of Kansas Press, 2, pp. U628-630.
Kier, P. M. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections 144, (3), 262 pp.
Lambert, J. 1918. Considerations sur la classification des echinides atelostomes. Memoirs de la Societe academique d\'Aube , serie 3 55, 9-54.
Philip, G. M. 1963. Two Australian Tertiary neolampadids, and the classification of cassiduloid echinoids. Palaeontology 6 (4), pp. 718-726