OPHIUROIDEA OF THE BAHAMA EXPEDITION. i$ 



The under side of the disk is pretty uniformly covered by 

 small rounded scales. Oral shields rather small, about as 

 long as broad, somewhat heart-shaped or triangular, with 

 curved edges; the outer end is usually slightly indented or 

 incurved, the lateral edges a little convex, the inner end acute. 

 Lateral oral shields oblong, a little wider distally. Mouth- papil- 

 lae squarish, about seven or eight on each side in a close row. 

 Tentacle-pores occur on only two basal joints, each has a 

 small rounded tentacle-scale. Under arm-plates, on the two 

 joints having tentacle-pores, are shield-shaped or pentagonal, 

 wider than long, broadest distally, with an obtuse inner angle; 

 farther out they are very small, triangular or short wedge- 

 shaped, but they are found well out on the arm. 



Arm-spines three, very small, short, and nearly equal near 

 the base of the arms, but beyond about the tenth joint the 

 lower one is a little the longest. The upper ones becoming 

 shorter and thicker, with a bent tip, which becomes claw-like 

 farther out. The spines are scarcely one-third as long as a 

 joint. Upper arm-plates very small, those beyond the basal are 

 top-shaped or wedge-shaped, with the distal end rounded and 

 the proximal end acute; they extend well out on the arms, or 

 as far as the arms are preserved in our specimens. 



Diameter of disk 7.5 mm.; length of longest arm (much 

 broken at the end) 22 mm. 



Off Havana, no to 260 fathoms, two examples. 



This species is closely related to O. cancellation Lyman. 

 The latter differs in having three pairs of tentacle-pores and 

 two tentacle-scales to each pore, smaller and shorter radial 

 shields, more widely separated, less unequal and more numer- 

 ous disk-scales; a much smaller super-marginal, interradial 

 plate; upper arm-plates larger and less triangular. The 

 prominent basal arm-plate, at the ends of the radial shields, is 

 lacking. 



The type of O.cancellatum Lym. was taken by the Challen- 

 ger Exp., off the coast of Japan, in 420 to 470 fathoms ( Voy. 



