Shell slender, conical, with curved axis; the curve lies in one plane as in the similar _Cornutella curvata_; the pores are smaller and more numerous than in this latter species, and the rounded apex bears no horn. _Dimensions._--Shell 0.12 to 0.16 long, 0.05 to 0.07 broad. _Habitat._--South Pacific, Station 300, depth 1375 fathoms. 3. _Cornutanna loxoconus_, n. sp. Shell wide, conical, with irregularly curved axis; the parts of the curve do not lie in one plane. Pores very small and numerous, of nearly equal size. _Dimensions._--Shell 0.2 long, 0.12 broad. _Habitat._--Tropical Pacific, Station 225, depth 4475 fathoms. Genus 528. _Archicorys_,[145] Haeckel, 1881, Prodromus, p. 427. _Definition._--#Archicorida# with simple urceolate or ovate shell, constricted towards the mouth. Apex armed with a horn. The genus _Archicorys_ and the following closely allied _Cyrtocalpis_ differ from the two preceding genera in the ovate or urceolate form of the shell, which is more or less constricted towards the terminal mouth. The upper pole in _Archicorys_ bears an apical horn, which is absent in _Cyrtocalpis_. The origin of these two genera may be the same, probably arising directly from Nassellida, and independently of the triradiate #Cyrtoidea# or bilocular #Spyroidea#. (Compare p. 1179.) 1. _Archicorys galea_, n. sp. Shell smooth urceolate. Pores large, in the middle part hexagonal, towards both ends smaller and polygonal. Apical horn stout, three-sided pyramidal, half as long as the shell. Mouth with a short tubular peristome, about one-third as broad as the shell. _Dimensions._--Shell (without horn) 0.15 long, 0.12 broad; horn 0.07 long, mouth 0.05 broad. _Habitat._--Central Pacific, Station 272, depth 2600 fathoms. 2. _Archicorys ampulla_, n. sp. Shell smooth, thin-walled, bottle-shaped, in the upper half conical, in the lower half inflate, subspherical. Pores subregular, circular, of the same breadth as the bars. Horn conical, stout, {1185}/about one-third as long as the shell. Mouth truncate, without peristome, about half as broad as the shell. _Dimensions._--Shell 0.15 long, 0.1 broad; horn 0.05, mouth 0.05. _Habitat._--Central Pacific, Station 268, depth 2900 fathoms. 3. _Archicorys microstoma_, n. sp. (Pl. 51, fig. 12). Shell rough, thick-walled, ovate. Pores large, subregular, circular, twice to four times as broad as the bars. Horn small, conical, not larger than one pore. Mouth very small, truncate, scarcely larger than one pore. _Dimensions._--Shell 0.1 long, 0.07 broad; horn 0.012, mouth 0.015. _Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms. 4. _Archicorys globosa_, n. sp. Shell nearly spherical, thorny, thick-walled. Pores very large, circular, separated by spinulate frames, smaller towards each pole. Horn conical, large, nearly as long as the radius of the shell; mouth truncate, simple, about one-third as broad as the shell. _Dimensions._--Shell diameter 0.13, horn 0.06, mouth 0.04.