MUSEUM OF COMPARATIVE ZOOLOGY. 21 



Amphiura argentea sp. nov. 



Plate XI. Figs. 388-290. 



Special Marks. — Disk scaled on both sides. One tentacle-scale. Radial 

 shields very small ; about twice as long as broad. Five or six short, conical 

 arm-spines. Upper arm-plates narrow and rounded. 



Description of an Individual ( Station 171). — Diameter of disk 4 mm. Length 

 of arm about 22 mm. Width of arm near disk 1 mm. One rather long, flat 

 papilla on either side of the base of the small, short mouth-angle, and a pair, 

 much rounded, at apex. Scales of first pair of mouth-tentacles long and rather 

 conspicuous. Mouth-shields much wider than long, rounded, with a wide curve 

 within, and outer side feebly curved. Side mouth-shields very narrow within, 

 where they meet ; wider without. First under arm-plate small and narrow, 

 being squeezed between the outer ends of the side mouth-shields ; those be- 

 yond are as broad as long, bounded without by a clean curve, on lateral sides 

 by slightly re-entering curves, and within by a truncated angle. Side arm- 

 plates very short, so that there is a considerable naked space between them on 

 the sides of the arm ; they stand well out, forming a strong spine-ridge. Upper 

 arm-plates narrow, longer than broad, nearly pentagonal, with rounded corners 

 and an angle inward. Disk delicate, covered above and below with minute, 

 thin, nearly uniform, overlapping scales ; 9 or 10 in the length of 1 mm. 

 where they are smallest. Radial shields very small, slightly sunken, of a pear- 

 seed shape, nearly or quite touching without, separated within by a narrow 

 wedge of minute scales ; length to breadth .9:. 3. Five or six short, nearly 

 equal, stout arm-spines, whereof the lower are cylindrical and tapering, and the 

 upper somewhat flattened and wider ; lengths to that of an under arm-plate, 

 .6, .6, .5, .6, .6, .7, .4. Near tip of arm there are three long, sharp, and very 

 slender spines^ twice as long as the arm-joints : this so great variation of 

 form is rare in Amphiura. One oval tentacle-scale. Color in alcohol, nearly 

 white. 



Station 171, 600 fathoms, 1 specimen. 



Amphiura acacia sp. nov. 



Plate XI. Figs. 392 - 294. 



Special Marks. — Disk scaled on both sides. One minute tentacle-scale. 

 Three short, moderately stout arm-spines. Radial shields short and wide. 



Description of an Individual (Station 235). — Diameter of disk 4.5 mm. Length 

 of arm, about 32 mm. Width of arm near disk, 1 mm. One flat rounded papilla 

 on each side of the mouth-angle, and a pair, blunt and thicker, at the apex. Scales 

 of the first pair of mouth-tentacles flat, and low down, so as to seem nearly on 

 a level with the outer mouth-papilla. Mouth-shields small, rounded, longer 

 than broad, widest without, and having a rounded point inward. Side liiouth- 

 shields three-sided, short and broad, .widely separated within. Under arm- 

 plates narrow, longer than broad, five-sided, with an angle within, outer side 



