193 

 Mr. Theodore Lyman presented the following : — 



DESCRIPTIONS OF NEW OPHIURID^, BELONGING TO THE SMITH- 

 SONIAN INSTITUTION AND TO THE MUSEUM OF COMPARATIVE 

 ZOOLOGY AT CAMBRIDGE. 



Amphiura (Forbes). 

 Ampliiura Piigetana^ (Lyman,) sp. nov. 



Description of a Specimen. Diameter of disc, 3.5 millim. 

 Length of arms, 24.5 millim. Greatest width of arm, without 

 spines, .7 millim. From outer edge of mouth-shield to outer cor- 

 ner of opposite mouth-slit, 1.5 millim. Mouth-shields nearly dia- 

 mond shaped, the outer and side angles slightly rounded ; length 

 to breadth, .3 : .2. Under anii-plates five-sided, with the fifth an- 

 gle directed inward ; length to breadth, near base of arm, .5 : .4. 

 Upper arm-plates bounded within by a strong arch, without by a 

 slight curve ; their lateral sides short ; length to breadth, near 

 base of arm, .5 : .7, — they do not quite touch each other. Scales 

 of disc mostly rounded, smaller below than above ; those above of 

 pretty even size, with a few little ones. Arm-spines 3 ; some- 

 times 4, on joints close to disc ; evenly tapering, moderately stout, 

 of even lengths ; length, near disc, .5 millim. Tentacle-scales 2, 

 small and rounded, placed obliquely side by side. Color, in alco- 

 hol : disc, above, light greenish gray ; below lighter, radial shields 

 darker ; arms, above and below, straw-color, with a faint white 

 line, running lengthwise above. 



Variations. The angles of the mouth-shields may be more or 

 less rounded. Among younger specimens, the scales of the disc 

 are more even in size, and the primary plates have their corners 

 not entirely rounded off. The proportion of the arms to the disc 

 varies somewhat, thus : diameter of disc to length of arms, as 

 3.5:24.5, 3:21, or 2.5 : 22.5. 



This species is distinguished from others of the genus, as fol- 

 lows : A. Orstedii has the radial shields longer and separated a 

 part of their length ; 4 or 5 spines and upper arm-plates broader. 

 A. Puntarence has rather longer arms, a small notch in the outer 

 side of the under arm-plates, and the upper arm-plates regularly 

 oval. A. violacea has mouth-shields proportionately much smaller 



proceedings B. S. N. H. VOL. VII. 13 FEBRUARY, 1860. 



