Page:Scientific results HMS Challenger vol 18 part 2.djvu/259

Synopsis of the Genera of Tripocalpida.

I. Subfamily Archipilida. Basal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell with three lateral ribs or wings, with or without terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with a horn,	496. Tripocalpis.
						No apical horn,	497. Tripodonium.
				Six to nine or more terminal feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	No apical horn,	498. Tripterocalpis.
				No terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with a horn,	499. Trissopilium.
						No apical horn,	500. Archipilium.
		Shell without lateral ribs or wings but with three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Feet simple or branched, not latticed.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Apex with a horn,	501. Tripilidium.
						No apical horn,	502. Tripodiscium.
				Feet latticed.		Apex with a horn,	503. Tridictyopus.
II. Subfamily Archiperida. Basal mouth of the shell closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell in its axis with a free (simple or branched) internal columella, prolonged into an apical horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell with three free feet, without lateral lattice-wings.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Columella simple,	504. Euscenium.
						Columella branched,	505. Cladoscenium.
				Shell with three lateral lattice-wings, connecting the three feet with the horn.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Columella simple,	506. Archiscenium.
						Columella branched,	507. Pteroscenium.
		Shell with simple cavity, without free columella. Three free basal feet.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	One apical horn,	508. Peridium.
						Two or more horns,	509. Archipera.
						No apical horn,	510. Archibursa.

Subfamily 1. Archipilida, Haeckel, 1881, Prodromus, p. 427.

Definition.—Tripocalpida with the basal mouth of the shell open (vel Monocyrtida triradiata aperta).

Genus 496. Tripocalpis,^[1] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex with a horn.

The genus Tripocalpis opens the series of Archipilida, or of those Monocyrtida in which the monothalamous shell exhibits a distinct triradial structure, and a simple open mouth, without cortinar lattice. Tripocalpis is probably the most primordial of the Archipilida, and has three lateral ribs, which are prolonged into three free terminal

1. Tripocalpis = Urn with three feet; τρίπους, καλπίς.