98 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



in large specimens by a very regular series of small dorsolateral spines and below by 

 one or two scries of robust superomarginal spines. R 66 mm., r 17 mm. R=3.88 

 r; breadth of ray at base 18 to 20 mm. (Attu Island). 



VerrilTs type and only listed specimen of tins variable form is a small example 

 from Unalaska. Under the caption of Asterias acervata he gives a good figure (pi. 

 106, fig. 3) of a variety from Kazan Bay, Atka. 1 have two specimens of the same 

 lot, collected by W. H. Dall, 1873. 



The type is an extreme variant of the form and is farthest removed in appear- 

 ance from nitida. I have three small examples of this subforma from Unalaska 

 (type locality, pi. 49, fig. 6), two small and one large specimen from Attu (pi. 49, 

 fig. 5) at the end of the Aleutian chain. Of the intermediate stages between this 

 extreme and acervate examples of nitida there is a pretty complete series. Scarcely 

 two specimens are alike. 



The large example from Attu (R 66 mm.) has the carinal line armed with very 

 prominent clusters of large capitate spines, three to five in a group, forming a zigzag 

 longiseries; 10 or 11 similar groups mark the primary plates of disk. These spines 

 are larger than any of the others, stand well above the general level, and have 

 convex, finely striated tops, upward of 1.75 mm. in diameter. On the inner side of 

 the broad supramarginal channel which is abactinal in position is a line of relatively 

 small capitate spines, fairly well spaced and not reaching end of ray. Scattered 

 between these and the carinal groups arc a relatively few similar spines which some- 

 times form a poorly defined series for a short distance. The spinulation between 

 the superomarginal and carinal series is characteristically meager, but this feature is 

 very variable in different specimens from the same locality. In the extreme as rep- 

 resented by the small type there may be only a single very interrupted series of small 

 dorsolateral spinelets, and a single irregular series of spaced subtruncate carinal 

 tubercles. 



The superomarginal spines are either one or two to a plate, usually one in the 

 small type form, but two in large specimens, where they stand close together on the 

 plate and form a prominent duplicate series defining the dorsolateral margin of the 

 ray, which is more definite and prominent than in nitida. Spines cylindrical, slightly 

 capitate, striate and subtruncate, about 1.25 mm. long, and a little bigger than the 

 dorsolateral spines. The intermarginal channel, though variable, is broad proximally 

 in both large and small examples. 



Inferomarginal spines usually one on the first three to six plates, then two, with 

 an occasional monacanthid plate; less often a plato carries three spines. A series of 

 similar actinal spines reaches about 0.8 R along ray, while a very short second series 

 is also present. These spines are cylindrical, round-tipped, and longer and thicker 

 than the superomarginals (about 2.5 mm.). In typical small specimens the spines 

 are more prominent and likely to be compressed; they form a bristling ventrolateral 

 border, and the actinal series is short. 



The first four to six adambulacral plates are monacanthid; then follow about 

 20 diplacanthid plates; then a variable number alternate with one and two spines. 

 About the last fourth or fifth of the ray has monacanthid plates (a plate bearing a 

 furrow spine alternating with one carrying a subambulacral). The spines are simi- 

 lar in form to those of nitida. Toward the mouth plates they gradually lengthen 



