Two new Cretaceous species of Sphynctolethus are described: Sphynctolethus harwoodii P.A.Sims & D.M.Williams sp. nov. and S. antarcticus P.Chambers & P.A.Sims sp. nov., both from New Zealand (Campbell Plateau, DSDP 29, site 275). A replaced name is given for the illegitimate name ‘Sphynctolethus pacificus’. While species in the genus possess a suite of characters, a common character appears to be the costate ocellus. Although that character is shared with other genera, it remains to be seen if it is actually a synapomorphy rather than homoplasious.