ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 57 



the peripheral. About three i)roininent hiteral infcromarfrinal spines in an oblique 

 series, with numerous accessory spinules on actinal surface. Adambulacral plates 

 with three furrow spines, and on actinal surface a lon<ritudinal series of two spines, 

 the adoral small, somewhat flattened, the other greatly enlarged, subterete at base 

 but much flattened beyond middle, and chisel-shaped or decidedly scoop-shaped 

 at tip. Out side of this series, three or four spines, about equal to adoral member 

 of above series, form an obhque irregular row or a group. 



Description. — Paxillsc fairly large, those on disk and along proximal radial 

 regions with spinelets very robust, short, globose, or with tips flattened and flaring. 

 In large specimens two or more central spinelets are frequently fused together to 

 form a very irregular plate or ossicle occupying the whole or a jiart of the tabulum 

 of paxilla. Peripheral spinelets or paxilla robust, but smaller than the central 

 ones; more uniform in size in small than in large sj)ecimens where they are of 

 unequal caliber, often enlarged at tips and ten to fi.fteen in number. Paxillae 

 largest on radial regions at base of ray, decreasing in size toward margin of area, 

 center of disk, as well as toward tip of ray. 



When the abactinal integument is removed and examined from the coelomic 

 side the midradial areas are seen to be paved with irregularly arranged, subcircular, 

 elliptical, or even faintly scalloped plates without papula; between them. The 

 areas occupied by these plates broaden at base of rays, and the central area of disk 

 is also paved Avith similar ossicles, decreasing in size and overlapping more and 

 more toward the very center. On the raj's, the nonpapular areas are from three 

 to four plates wide. On either side of this midradial area the plates are very 

 much smaUer, and at base of ra}' are not very regularly substellate or six-lobed, 

 but soon become elongate as in the foUowing species. The plates do not touch 

 and are surrounded by six or five papula\ On the interradial papidar areas of 

 disk the plates are stellate and usually touch. The connective tissue and muscle 

 layer between the ossicles and ccelomic epithehum is thicker than in either of the 

 following species. The arrangement of plates surrounding madreporic canal 

 resembles that of A. calif ornicus. 



Superomarginal plates very massive and high, especially interradially, occu- 

 pying two-thirds or tlu'ee-fourths of the vertical side of ray, and encroaching 

 conspicuously onto abactinal surface, about which they form a slightly raised 

 border. There is a large degree of variation both m the size and amount of encroach- 

 ment onto abactinal paxillar area. Variability in the latter respect afl'ects the 

 width of the paxillar area and considerably alters the general facies of the specimen. 

 A large specimen" {Albatross, 1904) from San Diego Bay (Beacon 3 Shoal) has a 

 row of small tubercles, one to a plate, all along the upper edge of series, extending 

 about two-thirds the length of ray. These tubercles are verj^ irregular in size and 

 shape, sometimes becoming reniform or even cordate. Not quite half way to lower 

 end of each plate is another small tubercle forming a similar but less conspicuous 

 longitudinal series. Another large specimen, that from which the diagnosis is 

 taken, has both series of tubercles well developed, the upper series extending 

 nearly to tip of ray, the lower within two plates. Spines of lower series conical 



"See pi. 5, fig. 2. 



