_Dimensions._--Diameter of the cube 0.08; length of the feet 0.07. _Habitat._--North Pacific, Station 241, depth 2300 fathoms. 7. _Acrocubus cortina_, n. sp. (Pl. 93, fig. 16). Mitral ring smaller than the basal, both rings elliptical, with curved rods. Sagittal ring ovate, prolonged upwards into an occipital horn, downwards into a caudal foot, as in the preceding species. As in the latter, also, the two lateral columellæ are prolonged downwards into two pectoral feet, but also upwards into two convergent horns, which are united with the occipital horn (commencing the formation of a galea). Rings and feet somewhat thorny. _Dimensions._--Diameter of the cube 0.16; total height 0.2. _Habitat._--Central Pacific, Station 266, depth 2750 fathoms. Subgenus 4. _Tetracubus_, Haeckel. _Definition._--Basal ring with four descending feet (two sagittal and two lateral). 8. _Acrocubus tetrapodius_, n. sp. Mitral and basal rings of the same size, square, with straight rods, sagittal ring also square. The four vertical columellæ are nearly parallel and straight, prolonged upwards into four short conical horns, downwards into four longer conical feet. (The shell has nearly the form of a geometrical cube, the eight corners of which are prolonged into eight vertical conical spines, four smaller ascending and four larger descending.) _Dimensions._--Diameter of the cube 0.09; length of the feet 0.06. _Habitat._--South Atlantic, Station 332, depth 2200 fathoms. {995}9. _Acrocubus amphithectus_, n. sp. (Pl. 93, fig. 17). Mitral ring smaller than the basal, both rings elliptical, with curved rods. Four columellæ thorny, also curved, divergent downwards, prolonged upwards into four thorny convergent horns, downwards into four larger branched divergent feet. The two sagittal horns and feet (anterior and posterior) are smaller than the two lateral (right and left); therefore the fundamental form of this species is distinctly amphithect (as in the _Ctenophora_). _Dimensions._--Breadth of the cube 0.12; total height 0.2. _Habitat._--South Pacific, Station 289, depth 2550 fathoms. Genus 427. _Toxarium_,[46] n. gen. _Definition._--#Tympanida# with two bisected horizontal rings, connected by four vertical columellæ. In the frontal plane two galear bows project upwards, and two thoracal bows downwards.