﻿]^Q8 OPHIACTIS KROYERI. 



Opliiactis Krbyeri Lutken. 



Ophinctis Krwjeri Lutkex. Yidensk. Meddflelser. Jan., 1856. 

 Ophiacik Kroijeri Lutken. Addit. ad Hist. Opli., p. 130. 



Special Marks. — Mouth-shields much broader than long, with a 

 peak within and a small tail without. Six (or five) arm-spines, all 

 smooth ; fourth (or third) from the top much the longest. 



Descr'qitlon of a Specimen. — Diameter of disk, 5"""-; from outer 

 side of mouth-shields to outer corner of opposite mouth-sht, 2.5"™-; 

 width of arm without spines, l.S"""- ; length of arm about 25"'"'- ; dis- 

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

 between outer corners of mouth-slits, .9 : 1.4. Mouth-pap illos, two to 

 each angle of jaw, thin, wider than long, with a bevelled, cutting edge. 

 Teeth nine, short, thick, stout, and crowded ; third and fourth from 

 below broadest ; uppermost one smallest and narrowest. Mouth-shields 

 much broader than long, with a little tail or peak without, and a 

 rounded peak within ; lateral corners rounded ; length to breadth, 

 .5 : .9. Side mouth-shields small, narroAv, irregularly triangular, not 

 meeting within ; they are unusually variable in size and shape. Under 

 arm-plates without sharp angles, broader than long, outer side and cor- 

 ners curved, lateral sides nearly straight, inner side strongly curved, 

 forming sometimes a rounded angle ; first plate short and very small, 

 often separated from second plate by side mouth-shields ; next three or 

 four plates smaller than those immediately beyond ; length to breadth 

 (eighth plate), .6 : 1. Side arm-plates projecting strongly, encroaching 

 a little below. Upper arm-plates a good deal broader than long, squar- 

 ish ; outer and lateral sides nearly straight, inner side slightly curved ; 

 corners a little rounded ; length to breadth (twelfth plate), .6:1; the 

 first two or three plates are smaller and oval. Disk-scales much crowded, 

 varying somewhat in length, but of nearly the same size ; about 12 to 

 a square mm. ; in the middle is a single primary plate, and there is a 

 connected, radiating row, of three or four plates, in each interbrachial 

 space ; along margin of disk, a good number of small. Stout, conical 

 spines, about .3""°- long ; there are a few others scattered on upper sur- 

 face of disk, and some on the interbrachial spaces below. Radial shields 

 swollen, long triangular, with their points inward ; where they are 

 joined, without, there is a slight lobe ; for the rest of their length they 

 are separated by a stout wedge of one, two, or three scales ; length to 

 breadth, 1.5 : .8. Arm-spines, near base of arm, six, very smooth, 

 rounded, hardly tapering, blunt and rounded at the point ; uppermost 

 and lowest spines shortest, fourth from the top the longest, others inter- 



