shell. Thorax subspherical. Abdomen nearly cylindrical, little contracted towards the peristome. Pores regular, circular, twice as broad in the thorax as in the abdomen, where they are separated by slight longitudinal ribs. Corona of the peristome composed of sixteen to twenty-four vertical, lamellar feet, which are longer than the abdomen, rectangular, and truncate at the end.
Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.05; breadth, a 0.03, b 0.11, c 0.09.
Habitat.—Central Pacific, Station 225, depth 4475 fathoms.
3. Calocyclas minervæ, n. sp.
Shell smooth, with two deep strictures, similar to Cycladophora stiligera. Length of the three joints = 1 : 4 : 3, breadth = 1 : 4 : 3. Cephalis subspherical, with a large, conical horn of three times the length. Thorax subspherical, with small, regular, circular pores. Abdomen cylindrical, with truncate mouth and few irregular pores of different sizes, commonly arranged in three or four subregular, transverse rows, with large intervening distances. Peristome with a corona of twelve to twenty vertical, lamellar feet, which are about as long as the abdomen, and truncate at the end (in Ehrenberg's figure these are broken off).
Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.02, b 0.09, c 0.07.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
4. Calocyclas amicæ, n. sp. (Pl. 74, fig. 2).
Shell smooth, with two slight strictures. Length of the three joints = 2 : 4 : 5, breadth = 2 : 5 : 5. Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate-conical; abdomen nearly cylindrical; both with small, subregular, circular pores. Peristome with a corona of twelve to fifteen small, triangular feet, only as large as the thickness of the shell-wall, and separated by distances of twice the size.
Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.1.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
5. Calocyclas sacerdotis, n. sp.
Shell smooth, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a pyramidal horn of three times the length. Thorax campanulate, conical; abdomen twice the length, cylindrical; both with small, regular, circular pores. Peristome somewhat constricted, with a corona of nine to twelve conical feet, which are as long as the cephalis, and with the ends curved inwards, protecting the mouth.
Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.12; breadth, a 0.03, b 0.09, c 0.09.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
6. Calocyclas vestalis, n. sp. (Pl. 74, fig. 3).
Shell smooth, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 3. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen
