﻿OPIIIACTIS VIRESCENS. 

 LIST OF SPECIMENS. 



113 



Ophiactis virescens Orsted & Lutken. 



Ophiactis virescens Lutken. Vidensk. Meddelelser. Jan., 1856. 

 Ophiactis virescens Lutken. Addit. ad Hist. Oph., p. 128. 



Special Marhs. — In well-grown specimens, the arm is suddenly swol- 

 len near the disk. Arm-spines very thick ; two uppermost usually 

 largest. Upper arm-plates twice as broad as long, with a distinct lobe 

 without. 



Description of a Specimen. — Diameter of disk, o.S""' ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 1.6"™- ; width 

 of arm without spmes, l.l"""-; length of arm, 15™"'; distance from outer 

 side of mouth-shields to inner points of teeth, to that between outer 

 corners of mouth-slits, .9 : .9. Moutli-papilla3, four to each angle of 

 mouth ; thin, flat, longer than broad. Teeth six, squarish, flat ; lowest 

 and uppermost one smallest ; those below thicker than upper ones. 

 Mouth-shields much rounded diamond-shape, with a point within, and 

 often a little tail without; length to breadth, .4 :.3. Side mouth-shields 

 very long and much bent ; they meet within, and run side by side 

 a little way, towards the teeth ; their outer ends meet those of their 

 neighbors, so as to cover the first under arm-plate. Under arm-plates 

 about as long as broad, octagonal, the inner laterals being usually a 

 little longer than the other sides ; length to breadth (eighth plate), 

 .5 : .4. Upper arm-plates oval, much broader than long, with a decided 

 lobe on outer side ; length to breadth (ninth plate), .5:1; first four or 

 five plates not so broad as those immediately beyond, because the ai'in 



