spine (c3) simple, lanceolate, shorter than the frontal spine. Eight tropical spines in the basal part smaller than the three former, but with much longer fork-branches, which are prolonged into very thin and long bristles. Eight polar spines rudimentary, very short.
Dimensions.—Length of the equatorial cross 0.4, breadth 0.3.
Habitat.—South Pacific, Station 295, surface.
3. Zygostaurus cornutus, n. sp.
Frontal spine (c1) little different from the two lateral spines, each with two divergent straight horns, which are shorter than the basal part. Caudal spine (c3) simple, triangular, shorter than the three former. Eight tropical spines of equal size and form, doubly forked, each with four thin, bristle-shaped, little divergent teeth. Eight polar spines short, simply forked.
Dimensions.—Length of the equatorial cross 0.5, breadth 0.4.
Habitat.—Indian Ocean (Madagascar), Rabbe, surface.
4. Zygostaurus caudatus, n. sp.
Frontal spine (c1) very different from the others, pincer-shaped, with two long, nearly parallel slightly bent horns. Lateral spines (c2 and c4) only half as long, with two short, nearly parallel horns. Caudal spine (c3) very long and stout, spindle-shaped, about twice as long as the frontal spine. Eight tropical spines of equal size and form, symmetrical, with two long and thin, divergent horns. Eight polar spines short and stout, with two divergent horns.
Dimensions.—Length of the equatorial cross 0.8, breadth 0.3.
Habitat.—Central Pacific, Station 265, surface.
5. Zygostaurus frontalis, n. sp.
Frontal spine (c1) very different from the others, with two very long, divergent, stout branches. Lateral spines (c2 and c4) only half as long, each with two stout, nearly parallel horns of equal length. Caudal spine (c3) simple, sword-like, shorter than the three former. Eight tropical spines of equal size and form, symmetrical, of the same shape as the two lateral, but only half as large. Eight polar spines very small, rudimentary, each with two short teeth.
Dimensions.—Length of the equatorial cross 0.7, breadth 0.5.
Habitat.—Central Pacific, Station 274, surface.
6. Zygostaurus sagittalis, n. sp. (Pl. 131, fig. 8).
Frontal spine (c1) very different from the others, with two equal, strongly divergent, bent horns. Lateral spines (c2 and c4) little smaller, but with two very unequal horns (the anterior shorter than the posterior). Caudal spine (c3) simple, sword-like or triangular, two-edged, longer
