JAPANESE ASTEROIDEA. 265 



" Cmspidaster Jiespovus, MÜLLER and Teoschel, sp. (PL XVII. figs. 

 5-7 ; PI. XVm. figs. 1-4). 



" Archeester hesperus, Müller and Teoschel, 1840, Monatsber. d. k. 

 Akad. d. Wiss. BerKn, -p. 104 ; System der Ästenden, 1842, p. 65. 



" Stellaster sulcatus, MÖBius, 1859, Neue Seesterne des Hamburger und 

 Kieler Museums, p. 11, Taf. iv. figs. 1 and 2 (Abliandl. a. d. Gebiete 

 Natmnv. hrsg. v. d. natm'wiss. Verein, Hambm-g, Bd. iv. Abtli. 2, 1860). 



"Kays five. 11 = 53 + mm. (the terminal plate being broken off in all 

 the rays of the largest specimen); r = 15mm. Breadth of the ray across 

 the second supero-marginal plates, 14.5 mm. 



" General form depressed and rigid. Rays moderately long and flat, 

 tapering from the base to the extremity, which is not attenuated or sharply 



" Abactinal area with paxillœ. Paxillae with very massive basement plates, suboval internal- 

 ly, pedicle coliunnar, crown with one or more central granules on the tabulum, surrounded by a 

 marginal series of short spinelets, which radiate horizontally, and are united, at least in part, 

 by a membranous web. 



" Adambulacral plates superficially subquadrangular or rhomboid ; the furrow margin with a 

 series of short, subcyhndric^l spinelets, five or six in number, forming a small radiating comb ; 

 the other three margins bearing small, skin-covered, papilliform spinelets, directed over a 

 channel which intervenes between adjacent adambulacral pLates, and also between the adambu- 

 lacral and the marginal plates. Actinal area of the adambulacral plates covered with sMn and 

 devoid of spines. Ambulacral fiurrows entirely closed by the adambulacral pLates and their 

 armature, when contracted. 



" Actinal interradial area well developed, with a few large plates, regular and pavement-like in 

 their disposition, covered with hyaUne deciduous granules, each plate margined with a webbed 

 fringe like that on the marginal plates ; well-defined channels along the suture hnes of the plates. 



" Superambulacral plates present. Tube-feet conically pointed. 



" No anus. No pediceUariœ. 



" Remarks. — The type of this remarkable genus is the starfish to which Ml'ller and 

 Teoschel gave the name of Archaster hesperus. Specimens, nearly all in a dry state, are to 

 be found in the British Museum, as well as in several of the Continental museums, but the 

 form has nevertheless been left in its anomalous position, although other observers have noted 

 some of its remarkable characters. Under these circumstances I have given below an account 

 in detail of its general structure. It will be seen to have nothing of generic imjaort in com- 

 mon with the two other members of Mulleb and Teoschel's genus Arcluister, Archaster typicus 

 and Archaster amjulatus, or indeed with the other forms which have been hitherto ranked as 

 Archaster. The presence of the superambulacral plates, the conical pointed tube-feet, the absence 

 of an anus, and also the absence of pediceUarire, would seem naturally to associate this form 

 with the Astropectinidœ, whilst the massive granulöse i)lates, devoid of all spines excepting the 

 lateral, with their singular marginal fringe, the character of the adambiolacral plates and their 

 armature, and likewise that of the actinal intermediate plates, constitute a series of structures 

 that isolates the form very distinctly from other genera at present known." 



