ECHINODERMS COLLECTED BY THE "HUXLEY," AUGUST, 1906. 535 



Ophiacantha bidentata, Eetzius. 



Asterias hidentata. Eetzius, 1805. 

 Ophinra Retzii. Nilsson, 1817. 

 Ophiocoma arctica. M. Troj. Si/st. Ast., 1842. 

 Ophiocoma echinulata. Forbes, 1852. 

 Ophiacantha Gh'osnlandica. M. Tr. Arch. f. Nat., 1844. 

 Ophiacantha. spimdosa. Sars, N'oj-g. Ech., 1861. 



Ophiacantha spimdosa. Lyman, III. Cat. Mus. C.Z., I., 1865, p. 93 

 and figure. 



Ophiacantha hidentata. Jeffrey Bell, Cat. Brit. Mus., p. 127. 



Station VII. ttt fathoms. 9 specimens. 

 Station X. 146 fathoms. 10 spechuens. 



0. hidentata was taken by the Talisman et Travailleur Expedition 

 between Lat. 19^ 19', Long. 20' 20', and Lat. 39° 33', Long. 12° 11' 30" 

 in depths from 1965 to 2590 metres. All the specimens were small, 

 the largest not more than 9 mm. diameter. 



It was found by the Candan Expedition in Lat. 45° 47', Long. 

 6° 15' in 17 metres. 



The largest of the Hnxlcij specimens has a disc diameter of only 

 5*5 mm., and the others are considerably smaller. Bell (1) gives the 

 disc diameter as 13 mm. The Huxley specimens are therefore 

 probably all young and immature. Descriptions of the species vary 

 in certain points. 



Bell (1) describes the mouth papillae as "not numerous," J3ut 

 inconstant in number, and to some extent in position, as is the 

 mouth shield in form. The disc covered with very short spines. 



Lyman (8) gives 0. spimdosa as the type of the genus, as its special 

 mark " Disc evenly covered with short spines." The mouth papillae, 

 however, he describes as " standing well apart ; six or seven to each 

 angle of the mouth — two outermost on each side small, flattened^ 

 somewhat rounded, blunt ; innermost one sharp, conical, rounded, 

 resembling the lowest tooth, which also might be well enough con- 

 sidered as a mouth papilla. Teeth seven." The Huxley specimens 

 agree in all these points, except that there are only four teeth. This 

 might be accounted for Ijy their age. 



Liitken (7) describes and figures 0. hidentata. The Huxley 

 specimens agree with the figure, except in the magnified appearance of 

 the spines. In the Huxley specimens the dorsal and ventral faces 

 of the disc are covered with short, smooth, cylindrical spines, in some 

 cases bifurcated. They stand on a slightly thorny stump or grain. 



