81 



flattened, and were cut square off at the end. Some well-grown 

 individuals have cross-bars of hght brown towards the end of the 

 arm. Sandwich Islands, Kingsmill Islands. 



Ophiocoma Saxxio, L}Tnan. 



Special marks. Arms to disc as four to one ; they are banded with 

 yellowish. Six arm-spines, slender, and elegant ; upper ones longest, 

 and as long as three and a half to four and a half under arm-plates. 



Description of a specimen. Diameter of disc 27 millim. Width of 

 arm, without spines, 4 millim. Length of arm about 90 millim. 

 Mouth-papillse, six, three on each side. Tooth-papillse irregularly 

 placed, extending nearly to the inner end of the mouth-shield, the 

 lowest one smallest ; about twenty-one in number. Teeth five, lowest 

 one very small and nearly surrounded by papillae ; upper one small 

 and somewhat pointed. Mouth-shields oval, longer than broad ; 

 length to breadth 2.5 : 2. Under arm-plates broader than long, regu- 

 lar, bounded witjiout and within by a curve, on the sides by re-enter- 

 ing curves ; length to breadth (10th plate) 1.4: 2. Upper arm-plates 

 very regular, bounded without by a clean curve, nearly oval, but 

 flattened a little within ; length to breadth (10th plate), 1.4 : 2.4. 

 Disc, above and on the sides, finely and closely granulated, about 45 

 grains to a square millim., brachial spaces below naked ; showing 

 unusually large scales, having a diameter of 5 millim. Arm-spines 

 six, remarkably slender, tapering, and regular ; lengths to that of 

 under arm-plate, 5.2, 6, 5, 4.2, 3.8, 3,2 : 1.4. Tentacle-scales two, 

 rather large and pointed. Color, in alcohol, above, very dark pur- 

 plish brown ; the disc ornamented with numerous fine radiating lines 

 of yellowish ; two yellowish specks at the base of each arm ; about 

 every other upper arm-plate is cross-barred with yellowish, the base 

 of the upper spine having the same color ; below, interbrachial spaces 

 dark brown, varied with yellowish ; yellowish spots between the under 

 arm-plates. 



Variations. The arrangement of colors on the disc varies ; some- 

 time the disc is wholly dark, or, again, only spotted with light yellow- 

 ish ; but the arms are always more or less banded with light. A light 

 mark on each side of the mouth-shield is x&ry characteristic. A 

 young specimen with a disc of 9 millim. had arms 34 millim. long ; 

 there were five arm-spines. Another had four, and close to the 

 disc, five arm-spines, the disc was to the arms as 6 : 21. In younger 

 specimens the tooth-papillas are, of course, fewer. 



This species stands very near 0. lineolata, from Isle de France, but 

 differs in having unequal and longer spines. Sandwich Islands, 

 KingsmiU Islands. 



PROCEEDINGS B. S. N. H.— VOL. VIII. 6 MAY, 1861. 



