30 OPHIURA RUBICUNDA. 



Ophiura rubicunda Lyman. 



Ophioderma rubicunda Lutkex. Yidensk. Meddelelser. Jan., 1856. 

 Ophioderma rubicunda Lutkex. Addit. ad Hist. Oph., p. 90. 



Special Marks. — Color, above, variegated lake-reel ; mouth-shields 

 much rovmded ; second mouth-papilla very broad ; side mouth-shields 

 naked. 



Description of a, Specimen. — Diameter of disk, 17.5""°'; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 6.8""- ; width 

 of arm, without spines, 3. 5°"°' ; length of arm, 103°"°- ; distance from 

 outer side of mouth-shield to inner points of teeth, to that between 

 outer corners of mouth-slits, 3.5 : 3.6. Mouth-papilla3, fourteen to six- 

 teen ; three outer ones broader than the rest ; second one, in particular, 

 very flat and broad, often as wide as .T""" ; other mouth-papillte flattened 

 spiniform ; two innermost ones somewhat broader, and shaped hke short 

 spear heads. Teeth five, short, flat, stout, with rounded edges, rather 

 broader than long, except uppermost one, which is longer and more 

 tapering. Mouth-shields crowded close against mouth-papillas, much 

 rounded, heart-shape, with point inward ; length to breadth, 2 : 2. Side 

 mouth-shields covered by grains, except a small round piece, which con- 

 nects mouth-shield with outer mouth-papilla and innermost under arm- 

 plate. Under arm-plates overlapping, rather broader than long, bounded 

 without by a clean curve, on the sides, by re-entering curves (where 

 tentacle-scales come), and within by two short, slightly-sloping, inner 

 laterals, and an inner side, which is a little re-enteringly curved ; length 

 to breadth (twelfth plate), 1.2 : 1.5. First plate diamond oval, length to 

 breadth, .7 : 1.3 ; second plate, length to breadth, 1.2 : 1.2 ; the plates 

 then grow proportionately wider to the seventh, which has the length 

 to breadth, 1.1 : 1.6 ; the proportions of twelfth plate are typical, and 

 are continued till close to tip of arm. Side arm-plates intruding a little 

 between upper arm-plates, but not meeting above and below till very 

 tip of arm. Upper arm-plates much broader than long, covering upper 

 surface of arm completely, so that side arm-plates are scarceh^ to be 

 seen ; outer and inner sides sensibly straight, the latter rather shorter, 

 so that lateral sides slope a little ; outer corners rounded, length to 

 breadth, 1:3; about two thirds out on arm same general shape, but 

 longer, length to breadth, .8 : 1.8 ; first three plates enclosed by scaly 

 prolongations of disk, and consequently more or less rudimentary, es- 

 pecially first plate, which almost disappears. Granulation of disk close, 

 fine, regular, covering every part, except radial shields, part of side 

 mouth-shields, and fine scales at base of arms, and extending quite to 

 base of mouth-papillae ; about 144 grains to a square mm. Radial shields 



