REPORT ON THE ASTEROIDEA. 149 
In a recent paper on the starfishes collected during the “Talisman” Expedition, 
M. Perrier’ 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,? 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 pedunculatus, E. P., Caulaster Sladeni, E. P.) sont 
earactérisés par l’absence presque compléte du squelette dorsal, représenté seulement 
par cinque bandelettes épineuses descendant du pédoncule dorsal et exactement inter- 
radiales.”* 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)," and is especially characteristic of the type of the genus, 
Porcellanaster cxruleus. 
Genus Styracaster, Sladen. 
Styracaster, Sladen, Journ. Linn. Soc. Lond. (Zool.), 1883, vol. xvii. p. 229. 
Rays 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-paxille. 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 adam- 
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 are. 
Remarks.—The form mentioned by Perrier,’ 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 carénés et portant des épines sur la caréne,” 
2 Comptes rendus, 1885, t. ci. p. 886. * Journ. Linn. Soc. Lond. (Zool.), 1883, vol. xvii. p. 217. 
* Loe. cit., p. 886. 4 Journ. Linn. Soc. Lond. (Zool.), 1883, vol. xvii. p. 214. 
5 Nouv. Archives Mus, Hist, Nat., 2c Série, 1884, t. vi. p. 272, 
