REPORT ON THE OPHIUROIDEA. 97 



.and flaring below ; lower interbracliial space occupied almost wholly by large genital 

 scales, and a marginal plate like a tubercle. 



(Type specimen from Station 122.) Diameter of disk 4 "5 mm. Length of arm about 

 7 mm. Width of arm close to disk, without spines, 1 mm. Mouth papilke closely soldered, 

 forming a straight line on the sides, with one round, bluntly pointed papillae at apex of 

 the jaw. Mouth shields small, triangular, with a long angle within, outer edge much 

 rounded ; length to breadth - 5 : '5. Side mouth shields large, long, and narrow, meeting 

 within, wider without than within, with outer ends rounded. First under arm plate of a 

 rude wedge shape, having the outer edge widest, and curved, long lateral sides slightly 

 re-enteringly curved, and a short blunt angle within ; second, third, and fourth plates 

 broader than long, much broader without than within, lateral sides with deep re-entering 

 curve, and outer side strongly curved ; fifth plate triangular, and much smaller ; beyond 

 which the plates are diamond-shape and minute. Side arm plates wide and swollen, 

 meeting broadly above and below ; beyond the sixth under arm plate forming almost the 

 entire covering of arm ; the second pair are very wide below, flattened and flaring, and 

 form a part of the disk margin. Upper arm plates small, broader than long, with outer 

 edge gently and inner edge deeply curved ; growing rapidly smaller, and almost disap- 

 pearing beyond the sixth. Disk thick and round, covered with swollen, microscopically 

 tuberculous plates ; in the centre are six primary plates, forming a regular rosette, the 

 central one pentagonal, the others hexagonal, and each bearing a large tubercle ; in the 

 interbrachial space there is one large square plate, also bearing a tubercle ; outside this is 

 a large, much swollen marginal plate, which is much wider without than within, the inner 

 edge being straight and the outer re-enteringly curved. Eadial shields large, rudely oval, 

 longer than broad, joined for nearly their whole length ; overlapped on their inner ends 

 by one of the primary plates, and separated without by a small, much swollen, semi- 

 circular plate ; length to breadth 1 : - 7. On the lower interbrachial space there are two 

 minute plates, just outside the mouth shield ; then the two great genital scales, which 

 occupy most of the space, and meet within at the mouth shield, and are separated without 

 by a large thick plate, wedged between them, which extends outward beyond the margin, 

 in form of a tubercle. The first side arm plate carries two short, thick, blunt arm spines; 

 the second, which forms part of the margin of the disk, has three spines ; the rest have 

 two, all situated low on the outer edge. One large, rounded tentacle scale on the 

 inner side of each tentacle pore of the first five under arm plates. Colour in alcohol, 

 white. 



By its curious, flaring under arm plates at the base of the arm, and its short, rapidly 

 tapering arm, this species gets a fanciful resemblance to some of the star-fishes. It is an 

 aberrant species, yet is correctly included by Sir Wyville Thomson under Ophiommium. 

 Its distribution is wide, and embraces the South Atlantic, including the Cape of Good 

 Hope; and in depth from 150 to 1675 fathoms. 



