the preceding genus Archicorys, from which it differs in the total absence of an apical horn. There is no trace of any triradial structure, excepting in some smaller species, in which the basal part of the central capsule is trilobate; these may be derived from the Dicyrtides Sethocorys or Dictyocephalus, by loss of the cephalis and the cortinar septum. But the larger species, which have a quite simple, ovate, central capsule (Pl. 51, fig. 13), have probably an independent origin, from Cystidium.
1. Cyrtocalpis urceolus, n. sp. (Pl. 51, fig. 13).
Shell smooth, urceolate, with very delicate and elegant network. Pores in the middle part large, regular, hexagonal, towards each pole smaller, irregular, roundish or polygonal. Mouth with broad, hyaline, annular peristome, about one-third as broad as the shell.
Dimensions.—Shell 0.16 long, 0.12 broad; mouth 0.05 broad.
Habitat.—Mediterranean (Portofino near Genoa), surface.
2. Cyrtocalpis reticulum, n. sp.
Shell smooth, urceolate, very similar to the preceding species, but differing from it in the densely reticulated framework of the shell, which is composed of very numerous and small, irregular, polygonal meshes of nearly equal size. Mouth without peristome, half as broad as the shell.
Dimensions.—Shell 0.18 long, 0.15 broad; mouth 0.07 broad.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
3. Cyrtocalpis amphora, Haeckel.
Shell smooth, urceolate with regular, circular pores of equal size, of about the same breadth as the bars. Mouth with smooth peristome, about half as broad as the shell.
Dimensions.—Shell 0.12 long, 0.08 broad; mouth 0.04 broad.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; surface, and at various depths.
4. Cyrtocalpis urna, Stöhr.
Shell smooth, urceolate, with subregular, circular pores of different sizes, gradually increasing towards the mouth, of about the same breadth as the bars. Mouth without peristome (?), about half as broad as the shell.
Dimensions.—Shell 0.09 long, 0.06 broad; mouth 0.035 broad.
Habitat.—Fossil in tertiary rocks of Sicily (Grotte).
