fourteen on the half equator of each chamber. Surface spiny, everywhere covered with small irregular thorns. (This species differs from the smooth Panartus tetrathalamus, Pl. 40, fig. 3, almost entirely by the thorny surface.)
Dimensions.—Main axis 0.2, equatorial axis 0.08; breadth of every chamber 0.1; meshes 0.005 to 0.01, bars 0.003, spines 0.01 to 0.02.
Habitat.—Cosmopolitan; on the surface of the Atlantic, Indian, and Pacific Oceans.
12. Panartus quadrigeminus, n. sp.
All four chambers of the cortical shell nearly of the same size and form, kidney-shaped, twice as broad as long. Pores irregular, polygonal (mostly pentagonal or hexagonal), six to eight times as broad as the thin bars; five to seven on the half meridian, twelve to sixteen on the half equator of each chamber. Surface of the cortical shell spiny, covered with numerous irregularly scattered, often oblique, bristle-like thorns.
Dimensions.—Main axis 0.27, equatorial axis 0.1; breadth of each chamber 0.13; meshes 0.01 to 0.02, bars 0.001 to 0.005.
Habitat.—Cosmopolitan; surface of the Atlantic and Pacific, many Stations.
Subgenus 4. Panartura, Haeckel.
Definition.—Surface of the cortical shell thorny, covered with scattered spines. Both its proximal chambers differ in form or structure from the two distal chambers.
13. Panartus spinosus, n. sp.
Both proximal chambers nearly ellipsoidal, with regular, circular pores enclosed by hexagonal frames. Both distal chambers conical, with a circle of ten to twelve large square pores at the base; the other pores small, roundish. The cortical shell of this species is quite the same as that of Panartus amphiconus (Pl. 40, fig. 5), but differs in the absence of the external envelope (or the second cortical shell), and is covered with short, conical spines on the whole surface.
Dimensions.—Total length of the cortical shell 0.25, greatest breadth (on the base of the distal chambers) 0.12; meshes of the proximal chambers 0.008, of the distal chambers 0.004; bars 0.002 to 0.04, spines 0.01 to 0.02.
Habitat.—North Pacific, Station 240, surface.
14. Panartus setosus, Haeckel.
Both proximal chambers kidney-shaped, broader than the two hemispherical distal chambers. Meshes of the cortical shell irregular, polygonal, or subregular hexagonal; at the base of each
