AND ECHINOIDEA OF THE KOEEAN SEA8. 



427 



AsTEOPECTEN JAPONicus, Muller Troschel. 

 1842. Astropecten japonicus, Muller 8f Troschel, System der Asteriden, 

 p. 73. 



Coll. St. John : Korean Straits, 9 fathoms. 



The arms are moderately long and narrow ; E= 11*25 millims., 

 r=4s millims. The foot-papillae, arranged in wedge-shaped groups 

 of five, are long, fine, and cylindrical. The first spinelet, which 

 forms the apex of the wedge, stands by itself, projecting inward 

 upon the furrow, is thicker than the rest and arched upwards at 

 its base ; the others stand external to this, two and two together, 

 the outermost pair being rather longer than the inner pair ; 

 whilst on the inmost portion of the furrow the outer series of 

 papillae are augmented by one or two additional spinelets. The 

 adambulacral plates which bear the foot-papillae appear very much 

 depressed, in consequence of the gibbous character of the ventro- 

 marginal plates — a feature which is very striking when compared, 

 for instance, with specimens of Astr. formosus, mihi, of nearly 

 equal size. 



The upper marginal plates are broader than long, and covered 

 closely with short stout granulose spinules of clavate form, and 

 on the outer half of the arm carry on their outer margin a small 

 conical spinelet. In the specimen under notice the nine outer, 

 out of thirteen marginal plates, are thus armed. 



The ventro-marginal plates project more outwardly than the 

 upper marginal plates, and bear one large, compressed, lanceolate 

 spine at the margin, which is generally followed by two smaller 

 spines placed side by side, not half its length, and very much finer 

 and more cylindrical. The rest of the spinulation consists of 

 small, short, isolated, cylindrical spinelets. In the present 

 example these have been very much abraded ; and little further 

 detail can be made out. 



The dorsal area or paxillary field is, in the middle of the arm, 

 very little, if any, broader than the marginal plate. The paxillae 

 are large and closely crowded — so much so that the radii (of which 

 there are 8-9 and very robust) of a paxilla are directed upward, 

 instead of at right angles to their pedicle ; and this gives to the 

 paxillary area a granulate rather than a stellate appearance to the 

 naked eye, and without any indication of regular arrangement. 



Dr. Liitken remarks* on never having seen an Astr. japonicus 



* ' Videnskabelige Meddelelser ' for 1864, p. 127. 



