﻿OPIIIURA TERES. 37 



Ophiura teres Lyman. (Fig. 1.) 

 Ophium teres Lymas. Pi-oceeil. Boston Soc. Nat. Hist., VII p. 198. 18G0. 



Sjiecial Marks. — A very large species. Upper arm-plates jjroken ; 

 arms short, romidecl. 



Description of a Specimen. — Diameter of disk, 32°""- ; outer edge of 

 mouth-shield to outer corner of opposite mouth-slit, 12""°- ; width of arm, 

 without spines, 7°"°' ; length of arm, 133°""- ; distance from outer side of 

 mouth-shield to inner points of mouth-papillae, to that between outer 

 corners of mouth-slits, 5 : 5.6. Mouth-papillae, about eighteen to each 

 angle of mouth, small, tooth-like, somewhat crowded ; the innermost, and 

 outermost but one, on each side, broader and larger than their neigh- 

 bors. Teeth six, broad, flat, short, with the free edge curved, the upper 

 ones more pointed. Mouth-shields very broad heart-shape, usually pre- 

 senting three rounded lobes, of which one is directed inward ; length to 

 breadth, 2.5 : 3.5. Side mouth-shields covered by granulation of disk. 

 Under arm-plates small, squarish, bounded -svithout hj three sides, with 

 much rounded angles, and -within by a shghtly curved line ; length to 

 breadth (thirteenth plate), 1.5 : 2. The 

 first five plates are smaller and narrower ; 

 and between the first and second, second 

 and third, and third and fourth, there is 

 a pair of pores. Upper arm-plates very 

 short and A\dde ; length to breadth, 1.7 : 6.5. 

 All the plates, except those just at the 

 tip of the arm, are broken in irregular 

 pieces ; those near base of arm usually m 

 five ; those near its tip, in three or four ; 

 so that the upper surface seems covered 

 with an irregular mosaic. Granulation of 

 disk fine and even, about 56 grains to a 



square mm., covering radial shields and the whole disk, above and 

 below ; near base of arms, above, are sometimes one or two little naked 

 plates of variable size. Arm-spines short, flat, tapering, rather stout, nine 

 in number ; three lowest ones rather longer than the rest, and lowest 

 one longest of all ; upper ones about half as long as side ann-plates. 

 Length of uppermost spine, .5"" ; of lowest one, 1.2"-. There are often 

 as many as eleven spines on joints near disk. Tentacle-scales longer 

 than broad, flattened; outside one rather shorter, and cut off more 

 square at the end. Color, in alcohol: above, purpli-sh brown, with 

 upper arm-plates closely speckled with fighter ; below, chewing appa- 



