REPORT ON THE !ASTEROIDEA. 355 
Family GYMNASTERIID &, Perrier, 1884. 
The older known genera included in this family were originally classed by Perrier’ in 
the Goniasteride. They were subsequently removed by Viguier,’ with the exception of 
Gymnasteria, to the Asterinide. Latterly, in the new classification proposed by M. 
Perrier,® they were separated as an independent family, Gymnasteria being taken as the 
type form and again united with the genera which were separated from it by Viguier. 
I fully concur in the course adopted by Perrier and maintain the family as established 
by him, notwithstanding the fact that more than one of the recently discovered genera 
appear to diminish considerably the difference supposed to exist between the Gymnas- 
teriidee and Asterinide. 
I have added several genera to those ranked by Perrier in the Gymnasteriidee, and 
of these one or two have unquestionably many affinities with the Asterinide ; but the 
balance of their structural ‘“ points” seems to me to warrant their classification with the 
Gymnasteriide. To those who take the broad view of taxonomic relationship inseparable 
from a theory of descent involving the assumption of organic form being dependent on 
variation and adaptation, this interlocking, as it might be termed, of allied families need 
not, in my opinion, invalidate the acceptance of the independent existence of two types 
or families, because some of their component forms show intermediate and transitional 
‘characters. This, indeed, seems to me to be a case which might be expected to occur 
under favourable circumstances ; although in general these intermediate phases have dis- 
appeared. 
Synopsis of the Genera included in the Family GYMNASTERIID®. 
A. Marginal and abactinal plates devoid of spines. 
a, Abactinal plates irrecular or substellate, not forming a composite reticulated 
mesh-work, Adambulacral armature: furrow series consisting of two 
spines; actinal spines one or two. Marginal plates large. A pair of 
specially localised pedicellariz at the base of the rays on the abactinal 
surface ns F 5 > , 7 ‘ 5 5 A ; .  Asteropsis. 
b. Abactinal plates forming a composite reticulated mesh-work. Adambulacral 
armature ; furrow series consisting of one spine ; one actinal spine. Mar- 
ginal plates small, pear-shaped, obliquely placed and strongly imbricating. 
No localised pedicellariz at the base of the rays . 5 : . . Dermasterias. 
B, Marginal plates with spines. , 
a. With a medio-radial series of large spines. Supero-marginal plates forming 
the margin, bearing large isolated spines. Abactinal plates rounded, 
forming regular longitudinal series : ¢ é C 6 : -  Gymnasteria. 
1 Reévis. Stell. Mus., p. 27 (Archives de Zool. expér., 1875, t. iv. p. 291). 
2 Archives de Zool. expér., 1878, t. vii. p. 204. 
3 Nouv. Archives Mus. Hist. Nat., 2c Sér., 1884, t. vi. p. 165. 
