the periphery, whilst the two proximal sides are straight). Radial spines thick, rounded; their outer conical part shorter than the inner cylindrical part.
Dimensions.—Diameter of the shell 0.1, of the parmal pores 0.01, of the sutural pores 0.01 to 0.02.
Habitat.—Tropical Atlantic (near Ascension), Station 345, depth 2010 fathoms.
6. Tessaraspis circularis, n. sp.
Parmal meshes circular, all eighty of equal size, quite regular, five to six times as broad as the thick bars, on an average larger than the roundish irregular sutural meshes. Radial spines quadrangular, prismatic, the outer part longer than the inner.
Dimensions.—Diameter of the shell 0.18, parmal pores 0.015 to 0.018, bars 0.003.
Habitat.—South-east Pacific, Station 300, surface.
7. Tessaraspis micropora, n. sp.
Parmal meshes circular, very small, all eighty of the same size, regular, scarcely as broad as the separating thick bars, and much smaller than the large irregular sutural meshes. Radial spines rounded, their outer conical part about as long as the inner cylindrical part.
Dimensions.—Diameter of the shell 0.08, of the parmal pores 0.003, of the sutural pores 0.005 to 0.015, bars 0.004.
Habitat.—Western Tropical Pacific, Station 225, surface.
8. Tessaraspis diodon, Haeckel.
Parmal meshes roundish, for the most part nearly circular, three to four times as broad as the bars, and on an average smaller than the roundish sutural meshes. Radial spines in the inner part cylindrical; the outer part very short (only one-third or one-fourth of the radius), divided completely into two parallel conical pointed teeth by a deep incision.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.01 to 0.012, of the sutural pores 0.01 to 0.03, bars 0.004.
Habitat.—Mediterranean (Messina), surface.
9. Tessaraspis quadriforis, n. sp.
Parmal meshes irregular, roundish, of nearly equal size, four to six times as broad as the bars, and on an average of the same size as the roundish sutural meshes. Radial spines quadrangular, prismatic in the inner part, which is somewhat longer than the conical outer part.
Dimensions.—Diameter of the shell 0.16, of the pores 0.012 to 0.018, bars 0.003.
Habitat.—North Atlantic, Canary and Cape Verde Islands, Station 353, surface.
