-"^ — -J r_ 



THE OPIIIURIDiE. 



167 



1 



I 



real papilla^ as it is not separated from tlie month skeleton. (The same is 



■ 



seen in most of the OphiacantJia species, more or less developed.) Mouth 

 shield very broad, triangular, more than twice as broad as long ; a very ob- 

 tuse angle within, side corners very acute, a little rounded at the tip ; inner 

 sides irregularly curved, outer sides almost straight, as is the outer edge ; 

 usually the whole outer side makes one straiglit line. Side mouth shields 

 rather broad, meeting within ; their inner side irregularly curved. Mouth 

 and side mouth shields quite flat, with sharp edges. 



First ventral plate rather large, five-sided, with an angle within. The 

 second is usually, but not always, in contact Avith the first, and has its acute 

 inner angle truncated; almost as long as broad. Those beyond all widely 

 separated, with an obtuse angle within ; considerably broader than long. 

 The second and third have the outer edge a little re-enteringly curved, 

 those beyond simply curved ; inner and outer laterals re-enteringly curved. 

 Side arm-plates with spine-ridge rather prominent. Dorsal plates rhom- 

 boidal, the second sometimes with inner angle truncated, those beyond 

 w^idely separated ; all the sides are a little curved, and all four angles rather 

 sharp ; sometimes the outer edge is simply curved, and the plates ai^e then 

 almost triangular ; they arc about equally long and broad. The arms are 

 not much knotted, tlie joints being inconsiderably constricted. 



Disk wdiolly covered with a dense coat of small, slender spines, c. 0.4 mm. 

 long, with a crown of 3-5 thorns (Plate XVL Fig. 11) ; also on the dorsal 

 side of the first free arm-joints such spines may be found. On the under 

 side of the disk the scales usually are seen beneath the spines. The radial 

 shields are wholly covered, but appear as indistinct, little elevated ribs. 



Five slender, smooth arm-spines, the two upper ones the longest, as long as 

 three arm-joints, the three lower ones much shorter, only about as long as 

 one joint. Farther out they are all only about as long as one joint. Some- 

 times there are 7-9 spines on the inner joints, and they may form an almost 

 continuous series over the dorsal side of the second joint. One pointed, 

 spine-like tentacle scale. 



Color in alcohol : pale gray. 



Several specimens from Station 3398, 1573 f. 



A rather fragile species. 



