roundish, double-contoured pores, irregularly disposed. Mouth constricted, two-thirds as broad as the thorax, with a broad, hyaline peristome.
Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.06 broad.
Habitat.—East coast of Australia, Station 164, surface.
7. Dictyocephalus mediterraneus, n. sp. (Pl. 62, fig. 2).
Shell rough, thin-walled, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 8. Cephalis hemispherical, with small, circular pores. Thorax ovate, truncate, with much larger circular pores of different sizes and thin bars between them. Mouth little constricted, two-thirds as broad as the thorax, with a narrow, hyaline peristome.
Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.08 broad.
Habitat.—Mediterranean, Smyrna (Haeckel), surface.
8. Dictyocephalus papillosus, Haeckel.
Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 7, breadth = 3 : 5. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, with larger, subregular, circular pores, separated by oblique series of conical papillæ. Mouth with a broad, hyaline peristome (the "third articulus" of Ehrenberg), separated by a stricture from the little broader thorax.
Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.05 broad.
Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.
9. Dictyocephalus tabulatus, n. sp.
Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 10, breadth = 3 : 7. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, truncate, with large, subregular, circular, hexagonally-framed pores. Mouth little constricted, nearly as broad as the thorax, with a broad, hyaline peristome.
Dimensions.—Cephalis 0.02 long, 0.03 broad, thorax 0.1 long, 0.07 broad.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
10. Dictyocephalus reticulum, Haeckel.
Shell thin-walled, smooth, with deep collar stricture. Length of the two joints = 2 : 8, breadth = 3 : 5. Cephalis subspherical, with small, circular pores. Thorax campanulate, with
