REPOET ON TILE ASTEROIDEA. 149 



In a recent paper on the starfishes collected during the "Talisman" Expedition, 

 M. Perrier 1 still maintains Caulaster as a distinct genus, and mentions the occurrence 

 of a second species, with which he has done me the honour of associating my name. 

 Unfortunately, however, no additional information is given on the structure of Caulaster. 

 Under these circumstances I feel assured that M. Perrier will acquit me of any undue 

 pertinacity in still upholding the opinion I expressed in 1883, 2 confronted as I am now 

 with the structure of Porcellanaster eremicus. No other course seems open to me, and I 

 am therefore reluctantly obliged to follow it so long as the present state of insufficient 

 information on the generic characters of Caulaster exists. 



The only remark upon the genus made by Perrier in the paper referred to is as 

 follows: — "Les Caulaster (Caulaster peclunculatus, E. P., Caulaster Sladeni, E. P.) sont 

 caracterise's par l'absence presque complete du squelette dorsal, represents seulement 

 par cinque bandelettes epineuses descendant du pedoncule dorsal et exactement inter- 

 radiales." 3 This limitation of the spinelets on the abactinal area to interradial bands 

 occurs in two of the species of Porcellanaster known to me (and mentioned in my 

 Preliminary Notices), 4 and is especially characteristic of the type of the genus, 

 Porcellanaster cseruleus. 



Genus Styracaster, Sladen. 

 Stijracaster, Sladen, Journ. Linn. Soc. Lond. (Zool.), 1883, vol. xvii. p. 229, 



Kays five, long and attenuate, incapable of being reverted. 



Supero-marginal plates meet in the median radial line, and encase the ray ; they 

 bear long, robust, cylindro-conical spines, which form a single series along the median 

 radial line. 



Abactinal area covered with membrane, beset with simple spiniferous spicules or 

 with pseudo-paxilla?. Usually no specially developed epiproctal prolongation is present, 

 but a more or less definite conical elevation may be formed. 



Actinal interradial areas paved with thin, smooth plates, arranged in regular columns, 

 more or less clearly imbricating, and covered with a delicate membrane. 



Ambulacral furrows narrow and more or less enclosed. Armature of the adain- 

 bulacral plates consisting of elongate needle-shaped spines, and with a tendency to 

 radiate apart. 



Cribriform organs three to seven in number in each interbrachial arc. 



Remarks. — The form mentioned by Perrier, 5 under the name of Machairaster pictus, 



as allied to Porcellanaster, but of which no generic diagnosis or description has yet 



been published, beyond the remark "a bras carenes et portant des opines sur la carene," 



1 Comptes rendus, 1885, t. ci. p. 886. a Journ. Linn. Soc. Lond. (Zool.), 1883, voL xvii. p. 217. 



3 Loc. cit., p. 886. 4 Journ. Linn. Soc. Lond. (Zool.), 1883, voL xvii p. 214. 



5 Nouv. Archives Hus. Hist. Nat, 2c S&ie, 1884, t vi. p. 272. 



