290 BULLKTIN 76, UNITED STATES NATIONAL MUSEUM. 



muliispina is gradual. The specimens jnay be considered from another point of 

 view as intcrgrades between leviuscula and multispina. I think it not improbable, 

 however, that dyscrita is an offshore variety or race of southern leviuscula, while 

 multispina bears a similar relationship to northern leviuscula. Certain intergrades 

 between true multispina and northern leviuscula are therefore difficult to separate 

 from some dyscrita. Owing to the extended distribution of the latter, occupying 

 as it does the shallower depths off middle and southern Cahfornia, it has seemed 

 better to recognize it as a special race rather than as a series of intergrading forms 

 only. The hypothesis as to its derivation would make such a course preferable 

 also. 



Rays of jnoderate thickness to slender; size rather small. R = 28 mm.; r = 7 

 mm.; R = 4 r. Breadth of ray at base 9 mm. R varies to shghtly more or less 

 than 4 r. 



Pseudopaxillse typically smaller than in leviuscula, being about as large as 

 intervening papular spaces or even smaller, and not so compactly placed as in 

 multispina, in which, even if small, the plates are closel}^ placed, leaving papular 

 areas decidedly smaller than the plates. A comparison of figures will demonstrate 

 this difference. There is less regularity in the shape of the pseudopaxillse than in 

 typical multispina. Spinelets typically like those of multisjnna, rather long, slender, 

 ending in a few sharp points or awns and joined at the base by a slight web (often 

 not present, or not visible). The number of spinelets is quite variable, but usually 

 ranges from fifteen to twenty-five to a plate (less than in multispina). Papulae 

 single, rather large. 



There are tliree regular series of plates external to the adambulacral plates, 

 similar to those of multispina. These are less conspicuous than in leviuscula, the 

 middle row having the largest plates, and are a little wider, to decidedly Avider 

 than long. A short row of small intermarginals at base of ray. 



Adambulacrals with one spinelet in the furrow except near tip of ray, where a 

 few plates have two. Adambulacral spinelets ten to fifteen, sometimes a few more 

 or a few less, the two or three largest standing on furrow margin, the others rapidly 

 growing smaller as they recede from furrow. There are two or three transverse 

 rows, and the spinelets themselves are round-tipped with numerous little prickles. 

 The armature is not essentially different from leviuscula variety B. The nearer to 

 leviuscula the specimen (as indicated by dorsal ])lates) the fewer the adambulacral 

 spinelets. 



Type.— Cat. No. 27780, U.S.N.M. 



Type-locality. — Albatross station 2907, near Point Conception, California, 44 

 fathoms, fine gray sand. 



Distrihution. — Middle and southern California, off shore to about 80 fathoms; 

 south of Monterey Bay this form predominates everywhere over leviuscula. 



