Page:Scientific results HMS Challenger vol 18 part 2.djvu/439

Synopsis of the Genera of Podocyrtida.

I. Subfamily Theopilida. (Podocyrtida aperta.) Terminal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A. Three free limbs or wings on the thorax (partly also on the abdomen).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	No free external appendages on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three wings of the thorax solid.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Wings arising from the thorax,	582. Pterocorys.
								Three ribs enclosed in the wall of the thorax,	583. Theopilium.
								Wings arising free from the collar stricture,	584. Corocalyptra.
						Three wings of the thorax latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Wings not prolonged into the cephalis,	585. Dictyoceras.
								Wings prolonged into the cephalis,	586. Pteropilium.
				Free appendages on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three ribs prolonged into three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Ribs and feet solid,	587. Theopodium.
								Ribs and feet latticed,	588. Pterocanium.
						Three free wings on the thorax. Numerous terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Wings and feet solid,	589. Pterocodon.
								Wings and feet latticed,	590. Dictyocodon.
		B. Free appendages not on the thorax, only on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen with three ribs and three feet,					591. Pleuropodium.
				Abdomen without lateral ribs, with three terminal feet.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Three feet solid, simple,	592. Podocyrtis.
								Three feet solid, ramified,	593. Thyrsocyrtis.
								Three feet latticed,	594. Dictyopodium.
II. Subfamily Theoperida. (Podocyrtida clausa.) Terminal mouth of the shell closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three lateral wings only on the thorax,					$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Wings solid,	595. Lithornithium.
								Wings latticed,	596. Sethornithium.
		Three lateral wings beginning from the thorax and prolonged into the abdomen,							597. Theopera.
		Three wings only on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spell spindle-shaped, with three lateral wings on the abdomen.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	No horn on the basal pole,	598. Rhopalocanium.
								Basal pole of the shell with a horn,	599. Rhopalatractus.
				Shell three-sided pyramidal, with three terminal-feet on the basal corners,					600. Lithochytris.

Subfamily 1. Theopilida, Haeckel, Prodromus, p. 435.

Definition.—Podocyrtida with the terminal mouth of the shell open (vel Tricyrtida triradiata aperta).