OPIIIOCNIDA SCABRIUSCULA. 



135 



arm. According" to Dr. LcConto, the color of the living animal would 

 seem to be the .same. 



Variations. — Dr. LcConte's original specimen has the outer side of 

 the upper arni-plates rather more curved, and almost without any 

 notch. 



0. hispida differs from 0. scahriuscida in having narrower under 

 arm-plates, rather longer arms, and longer and sharper spines on the 

 disk ; the markings, also, are black, instead of light green. 



LIST OF SPECIMENS. 



Ophiocnida scabriuscula Lyman. 



Amphiura scabriuscula Lutken. Addit. ad Hist. Opii., p. 118. 1859. 



Special Marks. — Arms six to eight times the diameter of the disk. 

 Small and very short spines on the disk. Arm-spines flattened. 



"""• • from outer 

 '^'^- • width 



Description of a Sjyecimen. — Diameter of disk, 8.5 

 side of mouth-shield to outer corner of opposite mouth-slit, 3.2 

 of arm without spines, 1.5"""" ; length of arm, 52"""- ; distance from outer 

 side of mouth-shield to inner points of mouth-pn]iillre, to that between 

 outer corners of mouth-slits, 1.7 : 1.5. Mouth-papilkie, six to each angle 

 of the mouth, small, rounded, separated, slightly flattened, nearly equal, 

 the innermost pair standing a little higher up than the others, and run- 

 ning upwards to the teeth. Teeth four ; upper one much the largest, 

 long, flat, moderately thick, with a slightly curved cutting edge ; two 

 next smaller, narrower, stouter, more rounded, with the edge thickened 

 at its middle point ; lowest one shaped like a broad, rounded, swelled 

 tubercle. Mouth-shields longer than broad, rounded within, prolonged 

 without, in a tail-like projection , inner end terminating in a rounded 



