128 ART. 2. — H. MATSÜMOTO : 



fine, imbricating scales, the latter bearing here and there very short, 

 acnte spines. The radial shields are very large, triangular, witli 

 rather acnte inner and perfectly rounded abradial angles ; the 

 adradial side is the longest, three-fourths as long as the disk 

 radius ; the shields are about twice as long as wide, and are 

 apposed to each other by the outer one-third to one-fourth of the 

 adradial sides. Interbrachial ventral surfaces covered by fine, 

 imbricating scales and beset with short, acute spines ; the latter 

 being less numerous than on the dorsal surface. 



Oral shields very small, triangular, with acute inner and 

 rounded outer angles, slightly longer than wide. Adorai shields 

 very large, long, stout, wider outwards, tapered inwards, meeting 

 with each other. Oral plates exceedingly small. Three or rarely 

 four oral papillae on either side ; the outermost one arises from 

 the adorai shield and is very large and unusually wide ; the rest 

 are very small ; there is often one additional infradental papilla. 

 Teeth four, blunt, with widened free end, except the uppermost 

 one, which is the longest and is acute. 



Arms slender and long, strongly knotted. Dorsal arm plates 

 very small, three- sided, with extremely wide inner angle and 

 curved outer border, extremely short, much wider than long. 

 Lateral arm plates extremely well developed, meeting each other 

 above and below, and so well soldered below that the line of 

 suture is hardly visible ; with well developed spine ridges ; strongly 

 constricted at the middle. First ventral arm plate exceedingly 

 small, pentagonal. The rest are quadrangular, with curved outer 

 side, wider than long, decreasing in size outwards. The arm 

 spines are needle-like, very long, acute. They are nine or ten in 

 number and approximated dorsally in the first two or three free 

 joints. In the first free joint, the uppermost spine is about three 



