Page:Scientific results HMS Challenger vol 18 part 2.djvu/94

Synopsis of the Genera of Coronida.

I. Subfamily Zygostephanida. Four lateral gates (no basal gate).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Two meridional rings (sagittal and frontal) complete, perpendicular to one another (no basal ring).	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Four lateral gates simple,			414. Zygostephanus.
				Four lateral gates partly latticed,			415. Zygostephanium.
II. Subfamily Acanthodesmida. Five large gates (four lateral and one simple basal).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Two meridional rings (sagittal and frontal) incomplete, both truncated by the complete horizontal basal ring.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Four lateral gates simple,			416. Coronidium.
				Four lateral gates partly latticed,			417. Acanthodesmia.
III. Subfamily Eucoronida. Six large gates (four lateral and two basal).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Two rings (the sagittal meridional ring and the horizontal basal ring) complete, the frontal meridian ring incomplete.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Basal ring without larger descending feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Gates simple,	418. Eucoronis.
						Gates partly latticed,	419. Plectocoronis.
				Basal ring with large, regularly disposed, descending feet. Gates simple,			420. Podocoronis.
IV. Subfamily Trissocyclida. Eight large gates (four upper lateral and four lower basal).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Two meridional rings (sagittal and frontal) and the horizontal basal ring complete. All three complete rings perpendicular to one another.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Four upper gates larger than the four lower.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Gates simple,	421. Tristephanium.
						Gates partly latticed,	422. Tricyclidium.
				All eight gates of equal size.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Gates simple,	423. Trissocircus.
						Gates partly latticed,	424. Trissocyclus.

Subfamily 1. Zygostephanida, Haeckel, 1881, Prodromus, p. 446.

Definition.—Coronida with four large lateral gates, without basal gate. Skeleton composed of two complete vertical rings, perpendicular one to another—the primary sagittal and the secondary frontal ring.

Genus 414. Zygostephanus,^[1] Haeckel, 1862, Monogr. d. Radiol., p. 268.

Definition.—Coronida with four large, simple, lateral gates, without basal gate and lattice-work. Skeleton composed of two simple meridional rings, perpendicular to one another.

The genus Zygostephanus, founded by me in 1862 for the Mediterranean Zygostephanus mülleri, is the simplest and most primitive of all the Coronida, and may

1. Zygostephanus = Yoked ring; ζυγόν, στέφανος.