Page:Scientific results HMS Challenger vol 18 part 1.djvu/693

5. Subfamily Euchitonida. Margin of the disk with radial chambered arms (or hollow chambered appendages), on the distal end of the arms with or without solid radial spines.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Two arms, opposite in one main axis.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Two arms simple, undivided.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Without a patagium,			223. Amphibrachium.
						With a patagium,			224. Amphymenium.
				Two arms forked (or one simple, other forked).	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Without a patagium,			225. Amphirrhopalum.
						With a patagium,			226. Amphicraspedum.
		Three arms (either regular, equal, or bilateral, with unequal arms).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three arms simple, undivided.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Without a patagium.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Regular,	227. Dictyastrum.
								Bilateral,	228. Rhopalastrum.
						With a patagium.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Regular,	229. Hymeniastrum.
								Bilateral,	230. Euchitonia.
				Three arms forked.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Either regular or bilateral.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Without a patagium,	231. Chitonastrum.
								With a patagium,	232. Trigonastrum.
		Four arms (either regular, with four equal crossed arms, or bilateral, with paired arms).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Four arms simple, undivided.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Without a patagium.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Regular,	233. Stauralastrum.
								Bilateral,	234. Hagiastrum.
						With a patagium.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Regular,	235. Histiastrum.
								Bilateral,	236. Tessarastrum.
						With a terminal patagial girdle,			237. Stephanastrum
				Four arms forked.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Without a patagium.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Regular,	238. Dicranastrum.
								Bilateral,	239. Myelastrum.
		Five arms (equal or unequal).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Five arms simple, undivided.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Without a patagium,			240. Pentalastrum.
						With a patagium,			241. Pentinastrum.
				Five arms forked.		Without a patagium,			242. Pentophiastrum.
		Six arms (equal or unequal).	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Six arms simple, undivided.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Without a patagium,			243. Hexalastrum.
						With a patagium,			244. Hexinastrum.

Subfamily 1. Archidiscida, Haeckel.

Definition.—Porodiscida with a simple spherical or lenticular latticed central chamber, surrounded by a single concentric latticed ring, which is divided by radial beams into two to six or more radial chambers.