Page:Scientific results HMS Challenger vol 18 part 1.djvu/1023

Rh same size as the sutural meshes. Radial spines cylindrical; their outer half on the pointed distal end two-edged and longer than the inner half.

Dimensions.—Diameter of the shell 0.14, of its meshes 0.008 to 0.016.

Habitat.—Mediterranean (Messina), North Atlantic (Canary Islands), Azores, surface.

5. Dorataspis typica, n. sp. (Pl. 138, figs. 4, 4a).

Shell with fifty-four crest-like sutures and fifty-four circular sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes of each plate elliptical, twice to three times as broad as the sutural meshes. Aspinal meshes of the four equatorial plates twice as broad as those of the sixteen other plates. The meshes are surrounded by elevated and denticulated crests (incipient spine-sheaths). Radial spines compressed, more or less two-edged; outer pointed half somewhat larger than the inner half. (In this typical species the composition of the shell prevailing in the majority of Ceriaspida is very clear.)

Dimensions.—Diameter of the shell 0.15 to 0.18, of the aspinal pores 0.02 to 0.03, of the sutural pores 0.01.

Habitat.—Central Pacific, Stations 270 to 274, surface and in various depths.

6. Dorataspis micropora, n. sp. (Pl. 138, fig. 3).

Shell with fifty-four sutures and fifty-four very small sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes of each plate elliptical, four to six times as broad as the sutural meshes. Radial spines in the outer half conical, somewhat shorter than in the inner cylindrical half.

Dimensions.—Diameter of the shell 0.11, of the aspinal pores 0.01 to 0.02, of the sutural pores 0.003.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

7. Dorataspis gladiata, n. sp.

Shell with fifty-four sutures and one hundred to one hundred and twenty sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes elliptical, three times as broad as the small sutural meshes; commonly two meshes in each suture. Radial spines sword-shaped, two-edged, tapering from the shell towards the two ends. (Resembles Belonaspis datura, Pl. 139, fig. 9, but differs in the spherical shell, the equal size of the four equatorial spines, and the absence of by-spines.)

Dimensions.—Diameter of the shell 0.12, of the aspinal pores 0.012, of the sutural pores 0.004.

Habitat.—Indian Ocean (Madagascar), Rabbe, surface.

8. Dorataspis polypora, n. sp.

Shell with fifty-four sutures and one hundred and sixty to two hundred sutural meshes, with eight hexagonal and twelve pentagonal plates. Commonly three meshes (sometimes four) on