1J.-0 l>l{Oi\ P. M. DUNCAN ON AN 



a space covered with skin between the side arm-plates. The sides 

 are re-enteringly curved, and much of their space corresponds to 

 the large tentacular opening. The third, fourth, and fifth lower 

 arm-plates correspond in shape with the second ; but towards the 

 tip of the arm the plates become smaller and longer than broad 

 and more constricted. 



The upper arm-plates are slightly broader than long, and are 

 convex from side to side ; they are boldly curved distally, and 

 their sides are outwardly curved. The first is hidden, and the 

 second is partly hidden proximally, by the meeting of the side 

 arm-plates. Towards the tip they become longer than broad and 

 rather angular distally. The side arm-plates form much of the 

 arm, and meet, both above and beneath the arm, along the median 

 line, and they form a long cylindrical tip to the arm. They are 

 narrowed just beyond the upper arm -plates ; they then swell out 

 and have convex sides. They are long, down the arm, and three 

 long, sharp, slender spines are on each near the disk ; but further 

 out two are seen on either side. The spines project outwards 

 from the arm, and are as long as the side arm-plate, or longer. 

 The lowest spine is the smallest ; and it is so placed on the 

 lower aspect of the side arm-plate as to occupy the position of a 

 tentacle-scale ; it projects downwards and sideways. Beneath 

 the arm the side arm-plates are large, and their length of median 

 junction is greater than above. The first pair are large, are 

 united orally, and in the midst, but at the distal end there is a 

 space which has already been mentioned, and it elongates towards 

 the tip of the arm. There are no proper tentacle-scales, and the 

 tentacles are long and stout. 



The colour of the specimen, which is dry, is white, and the 

 upper arm-plates are beautifully cellular. 



The length of the specimen is about -J inch. 



Locality. Agulhas Bank. Collected by Dr. Wallich. 



Itemarks. — Although the specimen to which this description 

 \ alludes is young, it is not immature, except in regard to the ends 

 of the arms. Its large plating on the disk, the naked under-disk, 

 the downward projection of the oral apparatus, the absence of 

 true mouth- and tooth-papillae, the comparative occlusion of the 

 interangular spaces, and the close fitting of the triangular-shaped 

 teeth, one and all, belong or relate to an Ophiurid which has all 

 its normal and most of the adult structures. 



The zoological position of the form is not without doubt j for 



