184 AKT. 2. — H. MATSUMOTO : 



the arms, and the interbrachial region of the disk is strongly- 

 convex below. Genital shts long. 



Oral shields rhomboidal, with the inner sides much longer 

 than the outer, with acute inner and rounded lateral and outer 

 angles, much longer than wide. Adorai shields triangular, tapered 

 within to a point, and not meeting with each other. Four oral 

 papillœ on either side of the oral angle, close-set, continuous, 

 subequal and blunt, the innermost one somewhat stouter. 



Dorsal arm plates oval, large, outer border curved, inner 

 border strongly convex, forming part of a circle ; as wide as the 

 arms, twice as wide as long, a little in contact with each other. 

 Lateral arm plates inserted like so many wedges between the 

 successive dorsal plates above and ventral plates below ; well 

 separated above but closer below. First ventral arm plate very 

 small, quadrangular, much wider than long. Those beyond 

 pentagonal, with very large inner angle and slightly notched outer 

 border, wider than long, only a little in contact with each other. 

 Three arm spines, conical, subequal, blunt, nearly as long as 

 the corresponding arm joint. Two tentacle scales, very flat and 

 thin ; abradial one smaller than the adradial, and overlapping its 

 base. 



Colour in alcohol light yellow. 



This species somewhat resembles 0. aßnis Duncan, especial- 

 ly in the number of the oral papillae, but differs from it in the shape 

 of the radial and oral shields and of the dorsal arm plates. In my 

 opinion, Ampliipholis andreœUàTKE]^, 1872, Amphiiira jjrœstans Kœh- 

 LEK, 1905, and Amphiodla perlei'cta Clakk, 1911, are referable to 

 OpJiiophragmiis, each showing certain affinities to the present species. 

 I have observed also in younger specimens of the present species 

 that, the marginal disk scales are so prominent as to form a hem-like 



