Page:Scientific results HMS Challenger vol 18 part 1.djvu/526

318 Dimensions.—Main axes of the four shells—(A) innermost 0.035, (B) second 0.08, (C) third 0.15, (D) outermost 0.2; their equatorial axes—(A) 0.03, (B) 0.08, (C) 0.12, (D) 0.16; pores 0.004 to 0.016, bars 0.002 to 0.004.

Habitat.—Western Tropical Pacific, Station 198, depth 2150 fathoms.

Definition.—Shell composed of five or more concentric shells (two medullary and three or more cortical).

2. Cromyodruppa mango, n. sp.

Shell composed of six ellipsoidal, concentric shells, two medullary and four cortical. Proportion of their main axes = 2 : 3 : 8 : 11 : 14 : 18. Network of the two medullary shells and of the innermost cortical shell subregular, with subcircular pores, about the same breadth as the bars. Network of the three outer cortical shells more lax, with larger, irregular, roundish pores, twice to six times as broad as the bars. The size of the pores and bars increases gradually from the innermost to the outermost shell. Surface smooth.

Dimensions.—Main axis of the six shells—(A) innermost 0.04, (B) 0.06, (C) 0.16, (D) 0.22, (E) 0.28, (F) 0.35; their equatorial axes—(A) innermost 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2, (F) 0.25; pores 0.003 to 0.02, bars 0.003 to 0.005.

Habitat.—Indian Ocean, surface; Matura, Ceylon, Haeckel.

Definition.— with four or more concentric shells (two medullary and two or more cortical shells), with numerous radial spines, but without polar tubes.

The genus Cromyocarpus differs from Cromyodruppa only in the development of numerous large radial spines which start from the outer surface of the shell. It exhibits therefore the same relation to the latter that Prunocarpus bears to Prunulum, or Druppocarpus to Druppula. It differs from both in the multiplication of the cortical shell.

1. Cromyocarpus quadrifarius, n. sp.

Shell composed of four concentric shells, two ellipsoidal cortical shells, and two spherical medullary shells. Proportion of their main axes = 10 : 8 : 3 : 2. Pores of the two cortical shells irregular, roundish, twice to four times as broad as the bars. Pores of the two medullary shells subregular, circular, about the same size as the bars. Outer surface covered with numerous conical radial spines, about half as long as the main axis, half as broad at the base as the innermost shell.