Shell ovate, rough, a little longer than broad. Pores regular, circular, hexagonally framed, of the same breadth as the bars. Basal plate (fig. 4) without larger pores. Horn pyramidal, stout, about half as long as the shell, with three short, horizontally divergent secondary spines at the base (possibly remnants of three original cortinar feet?) _Dimensions._--Shell 0.11 long, 0.09 broad; horn 0.06 long. _Habitat._--Central Pacific, Station 272, depth 2600 fathoms. 3. _Halicapsa prunoides_, n. sp. Shell pear-shaped, tuberculate, a little longer than broad. Pores irregular, roundish, of different sizes. Basal plate with four larger and six smaller pores. Horn pyramidal, stout, about one-third as long as the shell. (May belong perhaps to the similar #Prunoidea# _Lithapium_, compare p. 303 and Pl. 14, figs. 8-10.) _Dimensions._--Shell 0.14 long, 0.12 broad; horn 0.05 long. _Habitat._--Fossil in Barbados. Subgenus 2. _Echinocapsa_, Haeckel, 1881, Prodromus, p. 429. _Definition._--Surface of the shell spiny, covered with thorns, papillæ or larger spines. 4. _Halicapsa papillata_, n. sp. Shell bottle-shaped, papillate, one and a half times as long as broad. Pores circular, much larger in the middle part than towards the poles. The elevated frames between them bear on the {1191}nodal points large blunt conical papillæ. Basal plate without larger pores. Horn three-sided pyramidal, one-third as long as the shell, gradually passing into the slender neck of the bottle. _Dimensions._--Shell 0.22 long, 0.15 broad; horn 0.07 long. _Habitat._--Central Pacific, Station 265, depth 2900 fathoms. 5. _Halicapsa pyriformis_, Haeckel. ? _Haliomma pyriforme_, Bailey, 1856, Amer. Journ. Sci. and Arts, vol xxii. p. 1, pl. i. fig. 29. Shell pear-shaped, a little longer than broad, covered with numerous short conical spines. Pores subregular, circular, of nearly equal size, twice as broad as the bars. Basal plate with four crossed larger ovate pores (two larger cardinal and two smaller jugular pores). Horn stout pyramidal, scarcely one-fourth as long as the shell. _Dimensions._--Shell 0.16 long, 0.14 broad; horn 0.04 long. _Habitat._--Fossil in Barbados, living in the North Pacific (Kamtschatka)? 6. _Halicapsa hystrix_, n. sp. (Pl. 53, figs. 5, 6). Shell pear-shaped, subspherical, a little longer than broad, with scattered stout pyramidal spines about as long as the radius of the shell. Pores subregular, circular, three times as broad as the bars. Basal plate (fig. 6) without larger pores. Horn very large, pyramidal, longer than the shell. _Dimensions._--Shell 0.1 long, 0.09 broad; horn 0.13 long. _Habitat._--Central Pacific, Station 274, depth 2750 fathoms. Genus 533. _Archicapsa_,[150] Haeckel, 1881, Prodromus, p. 428. _Definition._--#Archicapsida# without apical horn.