REPORT ON THE ASTEROIDEA. 375 
Asterinidze the genera Porania, Dermasterias, and Asteropsis, which are now placed 
in the family Gymnasteriide. I maintain the composition of the family Asterinide as 
defined by Perrier? in 1875. 
In addition to the genera enumerated by him I have included Cycethra, a form since 
described, whose structural characters seem to me to place it amongst the Asterinide. 
I have also added in the following list another genus, Stegnaster (n. gen.), which seems to 
me necessary. The type of Stegnaster is the starfish described by Hutton” under the 
name of Pteraster inflatus, and subsequently placed under Palmipes by Perrier.’ I 
consider that the disposition of the papule, the membranous investment of the abactinal 
area (with the absence of the characteristic tufts of spines and the presence of granules), 
and the simple character of the armature of the adambulacral plates are sufficient to 
warrant the generic separation of this form from Palmipes. I also refer to the same 
genus Asterina wessel, though not without some hesitation, as the examples I have seen 
of that species appear to me to be immature forms. 
So far as I can judge from the description * and figure ® of Tremaster given by Verrill, 
I consider that the genus also belongs to this family, but from want of knowledge of its 
structure, I am unable to say whether its affinities are nearest to Palmipes or Asterina. 
No remark is made by the author as to the function of the extraordinary interradial 
apertures, and no suggestion is offered as to whether they are in relation with papular 
organs, or lead to a nidamental cavity. The circumstance of their opening on both the 
abactinal and actinal surfaces would seem to be at variance with such a supposition. 
Synopsis of the Genera included in the Fanily Astertwip&. 
A. Marginal plates large; and superficially phanerozonid in character. . GANERIINE, 
a, Spinelets on the abactinal plates spiniform, disposed in paxille-like 
groups. No differentiated median band; all the abactinal 
plates subsimilar. Marginal plates with a vertical group of 
spinelets. Actinal intermediate plates with small groups of 
spinelets . : = A 5 ° . . 3 : Cycethra. 
b. Spinelets on the abactinal plates small, often in arcuate series. A 
more or less distinctly defined band of slightly differently shaped 
plates along the median radial line. Marginal plates with a 
vertical single series of spines forming a sort of comb. Actinal 
intermediate plates with large spines (1-2) not forming a 
group . : ; A ; : : : ‘ : é r Ganeria. 
1 Révis. Stell. Mus., p. 28 (Archives de Zool. expér., 1875, t. iv. p. 292). 
2 Cat. Echin. New Zealand, 1872, p. 10. 
3 Révis. Stell. Mus., p. 291 (Archives de Zool. expér., 1876, t. v. p. 211). 
4 Proc. U.S. Nat. Mus., 1879, Nov., p. 201. 
5 Rep. Commiss. Fish and Fisheries for 1883, Washington, 1885, pl. xviii. fig. 51.- 
