252 ART. 2. — H. MATSUMOTO : 



squarish, wider than long, soldered together. Teeth short, rather 

 triangular, stout. 



Arms tapered rather rapidly. Dorsal arm plates triangular, 

 with acute inner angle and very convex outer side, about as wide 

 as long, surface very convex. They extend nearly to the extremity 

 of the arms, where they are very rudimentary. Lateral arm 

 plates well developed, conspicuously flared, very convex, meeting 

 both above and below. First ventral arm plate rhomboidal, not 

 very small, as long as wide, inner sides longer than the outer. 

 The second plate, which is the largest, is triangular, with very 

 convex outer side, much wider than long. Those beyond similar 

 to it but smaller, constantly diminishing in size outwards. Three 

 arm spines, needle-like, acute, well spaced ; the middle one longer 

 than the rest, and about two -thirds as long as the corresponding 

 arm joint. Second oral tentacle pore opening entirely outside the 

 oral slit, bounded by about four scales both on the abradial and 

 adradial border. Tentacle pores eight or nine pairs to each arm, 

 very small, destitute of any scales, or a small one may be present 

 on the adorai side in the basal joints. 



Colour in alcohol : disk yellowish gray above and white below ; 

 arms white. 



In the specimen from the Uraga Channel, the disk is covered 

 over only by the primaries and radial shields, without any inter- 

 vening smaller scales ; and the central bosses of the six primaries 

 are not very conspicuous. 



This species differs from A. minuta (Lyman) in the presence 

 of a central boss on the central and radiais, in the well developed 

 arm combs, in the presence of the dorsal arm plates, and 

 in the strongly flared lateral arm plates ; and fi'om A. forbesi 

 (Duncan) in the presence of a central boss on the six primaries, 



