﻿132 OPIilOPilUAGMUS WURDEMANII. 



Ophiophragmus Wurdenianii Lyman. 



Ampldura Wurdemanii Lymax. Proceed. Boston Soc. Nat. Hist., VII. p. 19G. 



Sjyecicd 3farks. — Disk-scales smooth, and not regularly arranged. 

 Mouth-shields long and narrow. 



Description of a Specimen. — Diameter of disk, 9.5""°- ; from outer 

 edge of mouth-shield to outer corner of opposite mouth-slit, 3.5""-; width 

 of arm without spines, 2.2""°-. Arms remarkably flat, wide, and little 

 tapering ; as they were broken, the length could not be known, but it 

 seemed not less than ten times the diameter of the disk. Distance from 

 outer edge of mouth-shield to mner points of mouth-papillaa, to that 

 between outer corners of mouth-slits, 1.6 : 1.5. Mouth-papillas, three on 

 each side, rounded and bead-like ; innermost one placed below the teeth, 

 and running somewhat upward. Teeth broad and flat, with free edge a 

 little curved. Mouth-shields shaped something like the sole of a shoe, 

 very long and narrow, small, with their outer end rounded, and their 

 inner one a rounded point, wider within than without ; length to 

 breadth, .8 : .5. Side mouth-shields almost as large as mouth-shields 

 proper, meeting within, somewhat curved. Under arm-plates squarish, 

 rather broader than long, overlapping each other a little ; outer side 

 bounded by a slightly re-entering curve, corners rounded ; length to 

 breadth (thirteenth plate), .5 : .7. Upper arm-plates very short and 

 broad, overlapping, bounded without by a re-entering curve ; outer cor- 

 ners strongly rounded ; length to breadth, .4 : 1.7 ; they are occasionally 

 broken in two. Scales of disk fine, of pretty even size, rather thicker 

 than are usually found in the genus, about 16 to a square mm. ; those 

 below somewhat finer. Radial shields broad, blunt, pear-seed shaped, 

 sometimes separated by a wedge of thi'ee or four scales, sometimes 

 joined by their sides ; length to breadth, 2 : 1. Arm-spines three, short, 

 stout, broad, rounded at the end, somewhat flattened, a little longer 

 than joints, neai'ly alike in shape and size. Tentacle-scales two, short, 

 broad, and thin, with curved edges. Color, in alcohol : above, disk 

 nearly white ; arms straAV-color, with irregular bands of dark brown ; 

 below, arms straw-color, interbrachial spaces white, mouth-shields 

 brown. 



This species belongs with those AmphiurjB that have the upper row 

 of the lower scales of the disk strongly developed and standing upright, 

 thus making a sort of fence. It differs from 0. septa* in the shape of 

 the mouth-shields, and in wanting spines on the upper surface of the 



* Ampldura septa Ltk. and A. maryinata Ltk. plainly belong in this genus. 



