210 ART. 2. — H. MATSUMOT.): 



or below, not in contact on the sides, bnt separated by a 

 naked space. First ventral arm plate very small, pentagonal or 

 quadrangular, wider within than without. Those beyond quad- 

 rangular, with convex inner side, notched outer side and rounded 

 outer angles ; wider than long, except the basal one or two ; the 

 successive plates are not in contact but separated by narrow 

 spaces, where the ventral ends of the lateral arm plates are 

 wedged in. Arm spines five in the basal joints, but four in the 

 middle part of the arms, subequal, but slightly longer downwards, 

 nearly equal to, or a little longer than, the corresponding arm 

 joint ; they are conical and obtuse in the proximal joints, but are 

 flattened more distally ; the second spine from below is especially 

 flattened and rather spur-shaped, with numerous thorns on the 

 very much flattened end ; the lowest one, as well as the third 

 from above is also somewhat thorny at the end. Tentacle pores 

 large, without scales. 



Colour in alcohol: disk gray, radial shields and arms straw- 

 yellow. 



A. œstuarii differs from A. phalerata (Lyman, 1874) and the 

 next species, A. radicola, in the shape of the radial shields, in 

 the much shorter arms and in the dorsal arm plates, which are 

 very wide even in the basal arm joints. A. œstuarii appears to 

 be closer to A. phalerata than to A. radicola in the arm spines, 

 which are four or five in number and less flattened and rather 

 conical in the basal arm joints. Further, A. œdnarii diflers from 

 A. ecnomiotata in the shape of the radial shields, and of the 

 dorsal and ventral arm plates, as well as in the fewer and less 

 thorny arm spines. 



A. œstuarii can be easily obtained together with A. euopla by 

 dredging in the muddy bottom of Aburatsubo Cove. It probably 



