2 THE VOYAGE OF H.M.S. CHALLENGER. 
should have chosen as the type of the family. From the fact, however, that the name 
has already passed into general use, and that a number of the deep-sea forms have been 
understood, at least conventionally, as belonging to that family, the designation has had 
a significance given to it beyond the scope of special students of the Asteroidea. Under 
these circumstances it seems to me better to avoid confusion by retaining the name of Archas- 
teride, than to give a new family name based on a genus that would be more generally 
typical of the group as a whole; though the latter course would have been undoubtedly 
preferable if the considerations I have mentioned above had not stood in the way. 
The following tabular arrangement will show the relations of the genera herein 
described, which are now classed in the family Archasteride; and also the four sub- 
families into which they are naturally divisible. 
Synopsis of Genera included in the Family ARCHASTERID&. 
A. No definite medio-radial line of abactinal plates. 
a. Papule confined to a limited area at the base of the ray. Marginal 
plates more or less alternate. Actinal intermediate plates 
absent or very few in number ¢ : : . PARARCHASTERINZ. 
a. With large odd interradial marginal plate aad spine. No true 
paxillz. Spicule bearing platesonly. Nospecialpapularorgan . - Pararchaster. 
6. No odd interradiai plate. True paxille. Special papular organ . ; Pontaster. 
b, Papule distributed over the whole abactinal area. Marginal plates 
opposite. Actinal intermediate plates well developed =. . PLUTONASTERINZ. 
a. Marginal plates more or less equally developed in each series. 
#, Supero-marginal plates thin and plate-formed; con- 
fined to the lateral wall; armed with a spine. No 
order of abactinal plates. Pedicellarie present . : Dytaster. 
6. Supero-marginal plates thick and massive, extending 
more or less on abactinal surface ; usually un- 
armed. Abactinal plates along the margin of 
the ray in more or less definite transverse series. 
No pedicellarie . : : ‘ ; : ; ; Plutonaster, 
b. Supero-marginal plates almost aborted. : ; : f : Lonchotaster. 
GB. With a definite medio-radial line of abactinal plates. 
a. Abactinal plates arranged in longitudinal series parallel to the 
median series. No internal imbricating ridges. Actinal inter- 
mediate plates well developed. No pedicellarie . 5 . PSEUDARCHASTERINE. 
a. Adambulacral armature : furrow series radiating, subpalmate ; 
actinal spines in a co-ordinated group. : : 5 Pseudarchaster. 
b, Adambulacral armature in longitudinal series parallel to the 
furrow. Post-adambulacral plates with fascioles . : : Aphroditaster. 
b. Abactinal plates in oblique transverse rows on each side of the 
median series. With special internal imbricating ridges. 
Actinal intermediate plates aborted or very few in number. 
Pedicellariz present . : . ARCHASTERINZ. 
a, Adambulacral armature Aeiopeceaoidl th Bbigue odie 
series. Flattened squamiform spinelets on infero-marginal 
plates . : : : é 5 : ; : : e Archaster. 
