﻿OPIIIOTIIUIX MAGNIFICA. 

 LIST OF SPECIMENS. 



169 



Ophiotkrix magnifica Lyman. 



Ophiothrix magnifica Lymax. Proceed. Boston Soc. Nat. Hist., VII. p. 254. 1860. 



Special Marks. — A large species ; back of disk closely spined ; arm- 

 spines stout, round, somewhat tapering ; color bluish. 



Description of a Sp)ecimen. — Diameter of disk, 12.5"""- ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 5.6°""-; width 

 of arm without spines, 2.7""''; length of arm, 70"™' ; distance from outer 

 side of mouth-shield to inner points of tooth-papillsB, to that between 

 outer corners of mouth-slits, 2.4 : 2.4. Tooth-papillae about thirty-six, 

 arranged in two rows of about ten each, which diverge from above 

 downward, and are filled in between by smaller papillse ; the papillte 

 grow shorter and smaller from above downward. Teeth six, squarish, 

 moderately stout, with rounded cutting edge ; uppermost one thin, and 

 so tapering as almost to be sharp. Mouth-shields small, almost circular ; 

 length to breadth, 1 : 1.2. Side mouth-shields meeting within. Under 

 arm-plates covered with thick skin, and closely joined, so that their 

 outline is indistinct ; in form irregular oval ; outer side longer than 

 inner, and slightly re-entering ; lateral sides well rounded ; length to 

 breadth, .7 : 1.3. Upper arm-plates small, with a strong median ridge ; 

 diamond-shaped, with outer angle much rounded, lateral angles sharp, 

 and inner angle very slightly truncated ; length to breadth (thirteenth 

 plate), .7 : 1.2. Brachial and interbrachial rays of disk closely beset 

 with round, stout, tapering spines, of very even length ; they are cov- 

 ered with minute thorns, and terminate in a rather blunt cro^m of 

 them ; these spines have usually a length of about Lo""""-. Radial 



