OniirRA TERES. 37 



Ophiura teres Lyman. (Ficr. i.) 



Ophiura teres Lyman. Proceed. Boston Soc. Nat. Ilist., VII p. 198. 1860. 



Sjyecial Mark'i. — A very large species. Upper arm-plates broken ; 

 arms short, rounded. 



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-papilla^, to that between outer 

 corners of mouth-slits, 5 : 5.6. Mouth-papillaj, 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- 

 l)Oi's. Teeth six, broad, flat, short, with the free edge curved, the upper 

 ones more pointed. Mouth-shields very broad heart-shape, usuall}^ 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 without by three sides, Avith 

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

 breadth (thirteenth plate), 1.5 : 2. The 

 fu'st 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 wide; 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 in 

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

 so that the upper surface seems covered 



.,1 • 1 • /^ 1 ,• r» Ophiura tons, (tyower side.) 



With an irregular mosaic, (iranulation ot ;,, imn-spiues. 



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 low^est ones rather longer than the rest, and lowest 

 one longest of all ; npper ones about half as long as side arm-plates. 

 Length of nppermost 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, purplish ])rown, with 

 upper arm-plates closely speckled with lighter ; ])elow, chewing appa- 



