﻿16 



OPHIURA. 



DESCEIPTIOX OF GENERA AND SPECIES. 



OPHIURA Lamk. {non Forbes). 



Type of the Gends, 0. Icevis. 



Ophiura Lamk. Syst. des Anim. sans Verteb. 1801. 

 Opldoderma Mull, and Tkosch. Syst. Asterid. 1842. 



Disk granulated ; teeth and mouth-papillge ; no tooth-papillfe ; spines 

 essentially smooth, shorter than the joints, flattened, numerous (7 to 13), 

 arranged along the outer edge of the side arm-plates ; two tentacle- 

 scales, the outside one covering the base of the lowest arm-spine ; no 

 ray-scales ; an indentation in the back of the disk, where it is joined by 

 the arm ; four genital slits, the first pair beginning outside the mouth- 

 shields. 



GROUPIKG OF SPECIES HEREIN DESCRIBED. 



Arm-spines equal, 



Lowest arm-spines longest, 



Side mouth-shields covered, 0. brevicauda. 

 I 0. hrevispina. 



Side mouth-shields naked, 



With radial shields, 



Without radial shields, 



Ophiura brevicauda Ltman. 



O. Holmesii. 

 Q. oUvacea. - 

 0. Januarii. 

 0. lavis. 

 0. cinerea.^ 

 0, rubicunda. 



O.panamensis. ^ ,,,^>, 



O. teres.* " 



0. oppressa. ^j^^^ 



Ophioderma brevicauda Lutkkx ; Vidonsk. IMeddelelser. Jan., 185G. 

 Ophioderma brevicauda LiJTKEN ; Addit. ad Hist. Oph. 94. 



Special i)/arA;s. — Granulation very coarse; arm-spines unusually short 

 and stout; arms generally not more than three or thi'ee and a half times 

 the diameter of disk. 



Description of a SjJecimen. — Diameter of disk, 20'""'-; from outer side 

 of mouth-shield to outer corner of opposite mouth-slit, 7°"°' ; width of 

 arm, without spines, 3.8""- ; length of arm, TT""' ; the distance from 

 outer side of mouth-shield to inner points of teeth is to that between 

 outer corners of mouth-slits as 3 : 4.2 ; mouth-papiliiB, eighteen ; outer 



The largest specimens have the radial shields often covered. 



