250 



BULLETIN 76, UNITED STATES NATION.\L MUSEUM. 



having, in fiill-grown examples, numerous abactinal pedicellarisc. The jaws are 

 low, rounded, and granuliform; two antl three jaws are commoner than four. The 

 anal opening is surrounded by numerous granuliform spinelets. Barring the small 

 pedicellarite the surface of the stai-fish is slick and smooth. The actinal interme- 

 diate areas are smooth, therefore, and are seamed mth minute lines or wrinkles 

 wliich have an interradial direction. 



The adambulacral plates are very small, wider than long, and no longer than 

 the width of the spine at base. The calcareous part of the furrow spine is tapering 

 and bluntly pointed. The spines are joined by a continuous web and capped by a 

 jirominent fleshy knob. The actinal spinelet is shorter (especiall}^ near base of ray), 

 flattened, broailly lanceolate, and often appressed to the adjacent actinal interme- 

 iliato plate, so that, on accoimt of the heavy skin, there appears to be, in such cases, no 

 actual spinelet. Toward extremity of ray the spinelets are upright and form a scal- 

 loped edge to the investing membrane. Adambulacral pedicellarise are not of constant 

 occurrence in northern examples, and have not been found in southern specimens. 



The abactinal skeleton is an open meshwork, consisting of rather widely sepa- 

 rated scalloped primary plates connected by numerous sUghtly overlapping elon- 

 gated ossicles forming narrow bands between the primary plates, as shown by the 

 figure. Agassiz's figure 3, plate 15, American Stai-fishes, shows tliis feature well. 

 In his figure 2 the ossicles appear more loosel}^ joined than normally, but the clear 

 description niakes the arrangement plain. The spaces between the meshes of the 

 skeleton, occupied chiefly by the papula, contain calcareous grammes, which on the 

 disk sometimes form short s])urs extending from the main trabeculje. (See PI. 49, 

 fig. 2, right-hand photograph.) 



Anatomical notes. — The intestinal coecum is a sac with five irregularly lobulated 

 short saccular divisions; aboral di\Tision of stomach large; hepatic cceca large, 

 reaching far along ray. Gonads in a thick tuft attached to the calcareous arch of 

 the interradial septa; from the point of attachment a tube (gonoduct) passes 

 upward for a short distance to the aboral surface. No superambulacral plates. 



Type-locality. — Sitka (Giiibe) . 



Distribution. — Sitka, Alaska, to Monterey Bay, CaUfornia, low tide and shallow 

 water, rocks. 



Specimens examined. — Twenty-two, from the following locaUties: 



Specimens of Dermasterias imbricata examined. 



Locality. 



s, southeastern Alaska Shore. 



Revillagidi'do Island, Alaska .do... 



Kaaaan Bay, I'rince of Wales Island, Alaska. . . .do. . . 



Naha Bay, Behm Canal, Alaska ...do... 



Barclay Sound, British Columbia do... 



I'uget Sound, Washington 'r.-do... 



Tacoma, Washington '.. .do... 



Kildare, Oregon j. . .do... 



Monterey Bay, Calilornia .do... 



Lieut.-Commander Nichols. 

 T. H. Streets 



.do.. 



Albatross, 1903 



Albatross, 1887-88 . 

 Chas. M. Drake... 

 Mrs. W. B. Hare.. 

 Oscar C. Sturges.. 

 D. S. Jordan 



Bur. of Fisheries. 

 U. S. Nat. Mus. 



Also numerous specimens in the Stanford collection from Half Moon Bay and 

 Monterey Bay, California. 



Remarks. — No other species has been described in tliis genus, and the genus 

 itself is sharply marked oft" from its nearest allies, Petricia and Asterope. 



