208 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



smaller disk, smaller actinal intermediate areas, and more numerous, 

 long, abactinal disk spines which are graduated in length into those 

 of the ray, not abruptly larger as in spinosus. B. spinosus is of a 

 much stouter habit, as is also B. mutahilis, which does not at all re- 

 semble moluccanus, having the abactinal spines abruptly larger in the 

 middle of the disk. B. acantJionotus differs in having a shorter fur- 

 row comb with 4 or 5 spines, several prominent accessory infero- 

 marginal spinules, and 1 to 6 accessory spinelets m connection with 

 the abactinal spines of disk, and the inferomarginal pedicellarige con- 

 fined to base of ray. 



BENTHOPECTEN POLYCTENIUS, new species. 



Closely related to B. violaceus (Alcock), but differing in having 

 abactmal pedicellarise, inferomarginal pedicellari^ far along the 

 ray (in adult specimens), more numerous furrow spines, and 20 

 instead of 24 adambulacral plates to the first 10 inferomarginals. 

 R = 224 mm., r=18 mm., R = 12 + r; breadth of ray at base, 23 mm. 

 Abactinal area of large specimen with numerous large pedicellarise 

 extending far along ray; abactmal plates with 4 to 8 short spinelets, 

 and scattered spmes on disk only; superomarginals ^\dth 1 spine, 

 together with 2 unequal accessor}^ spinules and 3 or 4 slender spinelets 

 proximally, and only 1 accessory spinule over most of ray; 2 infero- 

 marginal spines; 2 subambulacral spines, with often a third, smaller 

 accessory; furrow spines 13 or 14 (9 or 10 on first 2 plates); 7 or 8 

 oral spines and 3 to 5 suboral spines; 20 adambulacral plates corre- 

 spond to the first 10 mferomarginals, omitting the odd plate. 



Type.—C&t. No. 32630, U.S.N.M. 



Type-locality. — Station 5654, Gulf of Boni, Celebes, 805 fathoms, 

 bottom not recorded; bottom temperature 38.3° F. 



The following are the differences between B. violaceus and B. 

 polyctenius of equal size, the type of the latter being much larger than 

 that of violaceus. 



B. violaceus. 

 24 adambulacral plates correspond to 



first 10 inferomarginals. 

 No abactinal pedicellarise. 



Inferomarginal pedicellarise in inter- 



brachial arcs only. 

 Furrow spines 7 or 8. 



B. polyctenius. 

 20 adambulacrals correspond to first 10 



inferomarginals. 

 Abactinal pedicellarise few, on disk only. 



(In the type, numerous on disk and 



rays.) 

 Inferomarginal pedicellarise in inter- 



brachial arcs and far along ray also. 

 Furrow spines 9 to 11 (as high as 13 or 14 



in type). 



BENTHOPECTEN STYRACIUS, new species. 



Similar in general appearance to B. violaceus but with numerous 

 abactinal pedicellarise, and \cvj large odd interradial superomarginal 

 spines; differing from B. polyctenius in having only 1 or 2 spinelets 



