356 THE VOYAGE OF H.M.S. CHALLENGER. 
b. With no median radial series. Abactinal plates not forming regular longi 
tudinal series. 
a. Abactinal area devoid of plating. Actinal intermediate plates 
forming isolated bands in transverse series. . Tylaster. 
b. Abactinal area plated. Actinal area with large pigane Gate nitae : 
«. Plates covered with membrane ; usually devoid of spines or 
only rare isolated ones woven ; . Porania. 
8. Plates usually spinous, or with the whole riamnteané cleaeie 
crowded with miliary spinelets. 
i. Margin angular, formed entirely by the infero- 
marginal plates. Supero-marginal plates hidden 
and inconspicuous. 
1. Infero-marginal plates with a flattened comb 
of spinelets, which form a broad marginal 
fringe . 4 “ Marginaster. 
2. Spines when borne on the mere plats 
grouped and inconspicuous, not forming 
a marginal fringe. 
1. Papule single and isolated. Adam- 
bulacral armature on the actinal 
surface of the plate in a grouped 
or double series : : .  Lhegaster. 
2. Papule grouped. Adambulacral 
armature on the actinal surface of 
the plate in a single series . . Poraniomorpha. 
i. Margin thick. Supero-marginal and infero-mar- ; 
ginal plates superposed. Supero-marginal plates 
well-developed and conspicuous, subequal to the 
infero-marginal plates. e 3 2 -  Lasiaster. 
Genus Gymnasteria, Gray. 
Asterope, Miiller and Troschel, Monatsber. d. k. Akad. d. Wiss. Berlin, April 1840, p. 104 (non 
Philippi, 1840). 
Gymnasteria, Gray, Ann. and Mag. Nat. Hist., 1840, vol. vi. p. 278. 
Asteropsis (pars), Miiller and Troschel, System der Asteriden, 1842, p. 62. 
This genus was first recognised by Miiller and Troschel in 1840 under the name of 
Asterope, the Asterias carinifera of Lamarck being the type form, The name Asterope, 
however, was employed by Philippi in the same year for a Crustacean genus, and was not 
again used by Miiller and Troschel. In their System der Asteriden, published in 
1842, the same type was referred to a new genus named Asteropsis, and with it were 
associated the Asterias pulvillus of O. F. Miiller and the Asterias vernicina of Lamarck. 
These three forms, however, constitute the types of three distinct genera, two of which 
were established by Gray in 1840 under the names of Gymnasteria and Porama, 
Asterias carinifera of Lamarck being referred to the former, and Asterias pulvillus, 
O. F. Miiller, to the latter. Gray’s names have consequently priority and are now 
