Page:Scientific results HMS Challenger vol 18 part 1.djvu/1053

Rh 5. Icosaspis spectabilis, n. sp.

Parmal meshes very different; in the centre of each plate four very large, pentagonal aspinal pores, and around these two to three circles of smaller polygonal coronal pores, which are very numerous, and not larger than the small sutural pores. Radial spines quadrangular, prismatic, stout, very long; the outer part two to three times as long as the inner.

Dimensions.—Diameter of the shell 0.4, of the larger aspinal meshes 0.03, of the outer meshes 0.002 to 0.02, bars 0.005.

Habitat.—South Atlantic, Station 333, surface.

6. Icosaspis multiforis, n. sp.

Parmal meshes very numerous, more than one hundred in each plate; in the centre four larger pear-shaped pores, and around these four to five circles of smaller pores, gradually smaller towards the margin of the plate; the sutural meshes also very small and numerous (more than fifty around each plate), so that the number of all the pores together amounts to two thousand or even more. Radial spines thin, cylindrical, very long.

Dimensions.—Diameter of the shell 0.32; larger aspinal pores 0.02, smaller 0.002 to 0.01; bars 0.003.

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

Definition.—Condyles of the neighbouring plates grown together, and sutures obliterated; therefore the whole shell forms a single piece of acanthin.

7. Icosaspis tetragonopa, Haeckel.

Haliommatidium tetragonopum, Haeckel, 1862, Monogr. d. Radiol., p.421, Taf. xxii. fig. 13.

Parmal meshes all of nearly equal size and form, square, three times as broad as the bars, little larger than the sutural meshes. In each plate commonly sixteen equal square meshes, viz., four primary aspinal and twelve secondary, surrounding the former as a square corona. Radial spines tetrapterous, stout; the outer pyramidal half somewhat longer than the inner. This species differs from the similar Icosaspis tabulata (Pl. 136, fig. 2) in the concrescence of the sutures, the smaller number of pores, and the form of the stouter spines. The figure in my Monograph, drawn from a broken fragment, is not quite correct.

Dimensions.—Diameter of the shell 0.18, pores 0.009, bars 0.003.

Habitat.—Mediterranean (Messina, Corfu), surface.

8. Icosaspis icosahedra, n. sp.

Parmal meshes of different size and form; in the centre of each plate a cross of four pentagonal, primary aspinal pores, surrounded by a complete corona of twelve to sixteen polygonal coronal