I - Helotholus sp. from sediments of the North Atlantic (station C 2104); II - Sethoconus (?) ga1ea Cleve, viewed somewhat from below (station 16); III - Cyrtoidae gen. sp. similar to Sethoconus (?) galea, but differentiated by the absence of stout apical horn and less greatly expanded "thorax" (station 384); IV - Cyrtoidae gen. sp. very similar to Acanthocorys macroceras Haeckel, but differentiated by the far less stout apical horn; viewed somewhat from below (station 446).