EEPORT ON THE KADIOLAEIA. 



485 



Synopsis of the Genera of the Porodiscida — coutinued. 



223. 



5. Subfamily 



Eucliitonida. 



Margin of the disk witli 

 radial chambered arms 

 (or hollow chambered - 

 appendages), on thedistal 

 end of the arms with 

 or without solid radial 

 spines. 



Two arms, 



opposite 



in one 



main axis. 



Two arms ( Without a patagium, 



simple, 

 undivided. ( With a patagium, 



Two arms 

 forked (or 

 one simple, 

 _ otherforked). 



Three 



arms 



(either 



regular. 



equal, or < 



bilateral, 



with 



unequal 



arms). 



Four arms 



(either 



regular, 



with four 



equal 



crossed 



arms, or 



bilateral, 



with 



paired 



arms). 



Five arms 

 (equal or 

 unequal). 



Six arms 

 (equal or 

 unequal). 



r 



Three arms 



simple, 

 imdivided. 



Three arms 

 forked. 



Without a patagium, 

 With a patagium, 



' Without a j ^'S''^'''' 

 patagium. | ^-^^^^^^^^ 



With a 

 patagium. 



r Either 

 -; regular or 

 ( bilateral. 



Regular, 



Bilateral, 



Without a 

 patagium. 



AmpliihracMnm. 



224. AmpJiymeimim. 



225. Ampliirrhopaliun. 



226. Amphicraspedum. 



227. Didyastrum. 



228. Rhopalastrum. 



229. Hymeniastnim. 



230. Euehitonia. 



231. Chitonastrum. 



With a 

 patagium, 232. 



Four arms 



.simple, 

 undivided. 



Eofiular, 



Four arms 

 forked. 



Five arms 



simple, 

 undivided. 



Five arms 

 forked. 



Without a ( 

 patagium. | j,^.^^^^^^^ 



With a j P^^g"^^'' 

 patagium. | ^-^^^^^^^ 



With a terminal patagial 

 girdle, 



( Withouta j ^''S"^^'' 

 \ patagium. y j>-^^^^^,^^^ 



Without a patagium. 

 With a patagium, 



\ Without a patagium, 



f Without a patagium. 



Six arras 

 simple, , 

 undivided. ( With a patagium 



233. 

 234. 

 235. 

 236. 



237. 



238. 

 239. 

 240. 

 241. 



242. 



243. 

 244. 



Trigonastrum. 



Stauralastrum. 



Hagiasirum. 



Histiastrum. 



Tesserastriim. 



Stephanadrum. 

 Dicranastruin. 



Mijelastrum. 



Perdalastrum. 



Pentinastrum. 



Pentuphiastrum. 



Hexalastrum. 

 Hexinastrum. 



Subfamily 1. Archidiscida, Haeckel. 



Definition. — P orodiscida 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. 



