Page:Scientific results HMS Challenger vol 18 part 2.djvu/587

Rh the others, twice as long as the eleventh, and twice as broad as the ninth joint. The constricted mouth on its lower surface is only one-third as broad. Cephalis small, hemispherical, with a short, conical horn. Peristome with a coronal of twenty to thirty delicate, partly confluent, vertical teeth.

Dimensions.—Length of the shell (with thirteen joints) 0.26, breadth 0.12.

Habitat.—South-Eastern Pacific, Station 299 (off Valparaiso), depth 2160 fathoms.

11. Cyrtophormis turricula, n. sp. (Pl. 75, fig. 5).

Shell smooth, slender, tower-shaped, with fourteen distinct strictures. The ten first joints are nearly equal in length. The twelfth joint is the largest, three to four times as long as each of the preceding, and broader than all the others, twice as broad as the suddenly constricted mouth. Pores small and numerous, regular, circular, quincuncial. Cephalis small, subspherical, with a pyramidal horn of three times the length. Peristome with a coronal of twenty to thirty very delicate, partly confluent, short, vertical teeth.

Dimensions.—Length of the shell (with fifteen joints) 0.3, breadth 0.1. Length of the twelfth joint 0.05.

Habitat.—South-Eastern Pacific, Station 298 (off Valparaiso), depth 2225 fathoms.

Definition.— with the terminal mouth of the shell fenestrated (vel Stichocyrtida multiradiata clausa).

Definition.— (vel Stichocyrtida multiradiata clausa) with six radial ribs or wings.

The genus Artophæna and the following genus Stichophæna represent together the small subfamily of Stichophænida, or of those in which the multiradiate shell is composed of numerous (four or more) joints, and closed at the end by a lattice-plate. The number of the lateral, solid, or latticed appendages is six in Artophæna, nine in Stichophæna. They may have been derived either from the Stichophormida by closure of the terminal mouth, or from the Stichoperida by intercalation of three or six interradial appendages.

1. Artophæna ærostatica, n. sp. (Pl. 75, fig. 4).

Shell four-jointed, with three sharp strictures and internal septa. The fourth joint is subspherical, longer than the three first joints together, and twice as broad as these. The second joint is