47G 



PEOF. P. M. DUNCAN ON SOME 



the broad top, or its top may be sharp. Sometimes the denticles 

 on the side are long enough to simulate hook-|)rocesses. The 

 third is slightly larger, and the others increase in length and size, 

 the maximum being reached on the shoulder of the arm, and before 

 the process of the side arm-plate is reached. Occasionally on 

 the top of the arm and on the extremity of the side arm-plate 

 there is a smaller needle-shaped spine without denticulation. The 

 spines as a whole are flat, striated, many-toothed, and end with 

 a sharp brush o£ thorns, or are blunt and rarely simple at the ter- 

 mination. All have a distinct boss-like base, and are glassy when 

 young, and more opaque when old and dry. 



The specimens present the appearance of having been vivipa- 

 rous. The diameter of the largest disk is -j^ inch, and its longest 

 arm is one inch in length. 



Locality. Korean Straits, 23 fathoms. Collected by Capt. Sfc. 

 John, E.N. 



In the British Museum. 



Variation. The disk is sometimes pentagonal in outline. The 

 whole of the disk is sometimes covered with a crowd of stumps 

 and the radial shields also, but the spinules appear in the inter- 

 brachial space and have three long thorns. 



No derm is seen in some specimens separating the radial shield 

 from its fellow. 



In young forms, the spines are shorter, sharper, with fewer 

 teeth, and are sometimes not quite straight ; the tooth-papillse are 

 not so numerous, the under arm-plates are longer and less curved 

 without, and there are fewer spines on the side arm-plates. 



This variable species is allied to Ophiotlirix spiculata, Le Conte, 

 and is the representative of O. violacea, Lk. 



Ophiothrix koeeana, variety, sp. and var. nov. 



The disk is circular in outline, and the interbrachial spaces 

 below are very tumid and project, being tinted at the edge pale 

 green, nearer the margin light red. The disk is coloured 

 light reddish brown, and the numerous short trifid stumps on it 

 are of a dark red colour. The arms are light red and violet in 

 tint, and there is a light streak with darker colour running down 

 the upper arm, the darker tint spreading. There is a line of dark 

 tint on the under arm on either side. The stumps on the disk 

 are separated and not crowded, and those on the interbrachial 

 space are longer and not coloured, being trifid and glassy. The 

 spines are seven or more towards the base, largely thorned and 



