314 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Superomarginals, 18 in number, are massive and in form are much 

 as in A. lionotus^ but more tumid interradially. They increase in 

 size up to the third, which is very broad and meets its fellow inter- 

 radially, thence they decrease rather rapidly in width, the first plate 

 and the fifth being about as long as width of dorsal surface, the sixth 

 and succeeding plates being a little longer than wide. The plates are 

 bordered by a moniliform series of tiny elongate granules, and the 

 surface is tumid, and marked by uneven elevations bearing deciduous 

 spherical granules singly, in groups, or in irregular lines, these being 

 all over the surface but most numerous on the rounded margin of ray. 

 The interbrachial plates are most tumid and have the most numerous 

 granules (upward of a hundred). Far along ray the plates are not 

 very tumid, but have slight uneven eminences and granules scattered 

 all over the surface. On the ray of A. lionotus the granules are only 

 on the edge, not scattered all over the plate. The longitudinal 

 suture along the side of ray, as well as the transverse sutures, are at 

 the bottom of a shallow sulcus, due to the tumidity of the plate. No 

 superomarginal pedicellariae. Terminal plate large, as broad as 

 long, with several tubercular granules on the blunt, rounded tip. 



Inferomarginals smaller than superomarginals and decreasing 

 regularlj' in size, being longer than wide beyond the fourth. They 

 form a tumid ventrolateral ridge all along the ray and each plate is 

 independently tumid, and provided with irregular eminences crowded 

 with lines of spherical granules, as in the case of the supero- 

 marginals. The first 5 or 6 plates, with an occasional omission, have 

 on the ventral surface or rounded margin a pedicellaria, with fan- 

 shaped jaws, guarded on either side by a prominent granule. The 

 plates are margined by small elongate immersed granules, which 

 overhang a narrow sutural groove. Interradially the plates as seen 

 from the side are nearly as thick as the superomarginals, but they 

 rapidly become smaller beyond the middle of ray. Ten infero- 

 marginals nearest middle of ray corresponding to 30 adambulacrals. 



Actinal interradial areas similar in appearance to those of A. calli- 

 'morphus and A. lionotus^ but pedicellariae more numerous and larger 

 than in the latter and about the same size -is in callimoi^hus. Plates 

 with 4 unequal sides, in 5 chevrons, with an unpaired plate at the 

 apex of each and an extra plate or two interradially adjacent to 

 margin. They extend to the fifth or sixth inferomarginal with 1 or 

 2 isolated plates reaching the eighth. They are bordered by small, 

 unequal, slightly compressed, subconical or subfoliaceous granules 

 similar to those of A. lionotus, but a little smaller. Three to 5 or 

 even 6 prominent tubercular acorn-shaped granules stand on the 

 surface of the plate in a group, a line, or scattered. These are a 

 trifle larger than the abactinal granules, much larger than the mar- 

 ginal granules, and slightly larger than the corresponding granules 



