﻿164 



OFHIOTHRIX VIOLACEA. 



else dull green or blue. The young, with a disk of 3°"°-, have arms 

 16""°- in length ; the disk is already closely covered with small spines, 

 each bearing a crown of three long, sharp thorns ; the arm-plates are 

 proportionately longer than in the adult, and the arm-spines have rather 

 longer thorns. Very often the adult has only spines of the smaller sort 

 on the disk. Some specimens have the disk as large as 7""°". 



0. angulata bears some resemblance to 0. violacea ; the latter, how- 

 ever, has not banded arms, and has no such variety of coloration when 

 living; moreover, 0. angulata is smaller, has under arm-plates pro- 

 portionately longer, arm-spines commonly more numerous, and about 

 eighteen tooth-papilliB, while 0. violacea has as many as thirty. It 

 differs from O. sjnculata and 0. dumosa in fewer tooth-papillie, shorter 

 arm-spines, and in being a smaller s^aecies. 



LIST OF SPECIMENS. 



WheDce obtained. 



133 

 134 

 135 

 390 



Museum of Comparative Zoology. 



Charleston, S. C. 

 Charleston, S. C. ? 

 Charleston, S^ C. 

 Waceamaw, S. C. 

 North Carolina. 



Prof. Agassiz. 



Prof. Agassiz. 

 Prof. Asassiz. 



Smithsonian Institution. 

 I 12-(- I South Carolina. j 



OpMothrix violacea Mull. & Trosch. 



Stella marina minor echinata purpurea? Sloane. Voy. to Jamaica, p. 272, pi. 244, f 8, 9. 1725. 

 Stella scolopendroides ; Jamaicens'is purpurea? Linck. De Stel. Mai-., p. 51. 1733. 

 Opldolhrix violacea MiJLL. & Trosch. Syst. Asterid., p. 115. 1842. 

 Ophlollirix caribaiahiiTKEH. Vidensk. Meddelelser. Jan., 1856. 

 Ophiothi-ix Kroi/eri LiiTKES. Vidensk. Meddelelser. Jan., 1856. 

 Opldolhrix violacea LiiTKEX. Addit. ad Hist. Oph., p. 150 1859. 



Sjjecial Marks. — Dark-puri3lish blue, with a white line along the 

 arm. Small, forked spines on the disk, with a few long ones. 



Description of a Specimen. — Diameter of disk, lO"""- ; from outer 

 side of mouth-shield to outer corner of opposite mouth-sHt, 4°"°- ; width 

 of arm withovit spines, 2.3°"°- ; length of arm, 62"'°- ; distance from outer 

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

 outer corners of mouth-slits, 2 : 1.7. Tooth-papillaj arranged in an oval 



