Page:Scientific results HMS Challenger vol 18 part 2.djvu/559

This page has been proofread, but needs to be validated.

REPORT ON THE RADIOLARIA

1435

Synopsis of the three Families and six Subfamilies of Stichocyrtida.

Family LXVIII. Podocampida. Three radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichopilida.
		Mouth closed,	Stichoperida.
Family LXIX. Phormocampida. Numerous radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichophormida.
		Mouth closed,	Stichophænida.
Family LXX. Lithocampida. No radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichocorida.
		Mouth closed,	Stichocapsida.

Family LXVIII. Podocampida, n. fam.

Artopilida et Artoperida, Stichopilida et Stichoperida, Haeckel, 1881, Prodromus, p. 437-439.

Definition.—Stichocyrtida triradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, and bearing three radial apophyses).

The family Podocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears three external radial apophyses. It may be divided into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichopilida (and the united Artopilida), closed by a lattice-plate in the Stichoperida (and the united Artoperida). The phylogenetic origin of the Podocampida may be found in the Podocyrtida (p. 1314).

Very few forms only of the Podocampida were hitherto known, viz., Stichopilium (Pterocodon) davisianum, and three fossil species from Barbados, figured by Ehrenberg; Artopera loxia (united by him with Lithornithium), and two species of Pteropilium (sphinx and bombus, both united by him with the three-jointed Pterocanium). In general, the triradiate Stichocyrtida are much rarer and much poorer in specific forms than the triradiate Tricyrtida, their ancestors. We have observed altogether only forty-four species, thirty Stichopilida, and fourteen Stichoperida; the former are disposed among seven, the latter among three genera.

The three radial apophyses appear either as lateral ribs or prominent wings in the thorax (Pl. 77, fig. 8-12), or as three terminal feet around the mouth (Pl. 97, fig. 15). Sometimes the ribs are replaced by three radial combs, or rows of spines, and these may be united by three divergent beams, forming three vaulted bridges with numerous bows (Pl. 75, figs. 10, 11). The lateral wings or ribs, as well as the terminal feet, are either solid or fenestrated.