ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS— FISHER 103 



There is evidence that D. robusta has a fissiparous young stage similar to that 

 of Sclerasterias. At station 3404, at which the type of robusta was taken, were dredged 

 nine broken arms of a young sea star which Ludwig calls "Hydrasterias (?), sp. nov." M 

 There is no disk and the longest arm is 24 mm. These resemble in a general way the 

 intermediate stage between the young and adult phases, described for Sclerasterias 

 euplecta. There is no special evidence of fissiparity except the apparent homology 

 just indicated. 



These probable young of robusta have similar pedicellariae to the adult. The 

 straight are conspicuous, slightly spatulate, and have a few teeth. I have found 

 one or two similar pedicellariae on the type of robusta. The carinal, one series of 

 dorsolateral, and the superomarginal plates each carry a small spine, and between 

 these the crossed pedicellariae are thickly scattered, as in the homologous stage of 

 Sclerasterias. The spines have not yet developed sheaths to carry the pedicellariae, 

 which are still absent also from the two inferomarginal spines. The tube-feet are 

 strongly four-ranked. 



DISTOLASTERIAS NIPON (Doderlein) 



Plate 43, Figure 5; Plate 60, Figures 2, 2a; Plate 81, Figure S 



Aslerias nipon Doderlein, Japanische Seesterne, Zoolog. Anz., vol. 25, 1902, p. 334 (Japan). 

 Distolasterias tricolor A. Djakonov, Zwei neue Seesterne aus dem Westlichen Nordpacific, 



Ann. Mus. Zool. Acad. Sci. U. R. S. S., vol 27, 1926 (1927), p. 315, pi. 22, figs. 3-8; pi. 



23, figs. 9, 10 (Peter the Great Bay, near Vladivostok). 



Diagnosis. — Rays 5. R 155 mm., r 21 mm., R = 7.4 r; breadth of ray at base, 

 23 mm. (Peter the Great Bay); R 176 mm., r 20 mm., R = 8 r; breadth of ray at base, 

 27 mm. (type, northeast coast Honshu, Japan). Disk small, rays slender. Abac- 

 tinal spines, surrounded by thick wreaths of crossed pedicellariae, well spaced, 2 to 

 4 mm. long, sharp or blunt, the distal tapered half with irregular coarse grooves or 

 channels; carinal spines in a definite series more closely set than the dorsolaterals, 

 which are not in definite longiseries (pi. 89, fig. 8); superomarginal spines one to a 

 plate, inferomarginals two to a plate, a little longer than abactinals, shallowly gouge- 

 shaped and subtruncate, sometimes bifid; adambulacral spines two, very slender, 

 nearly as long as inner inferomarginals; straight pedicellariae, lanceolate, slender; 

 crossed pedicellariae with two prominent terminal fangs. 



Description. — The general habit is indicated by Figure 8, Plate 81, a specimen 

 from Peter the Great Bay (near Vladivostok) and now in the Museum of Compara- 

 tive Zoology. A similar specimen was forwarded to the writer by Doctor Djakonov. 



The largest example recorded by Djakonov has R 233 mm., r 35 mm. In his 

 specimens, R varies from a little less than 7 r to 8 and 9 r. My large Hong Kong 

 example measures R 200 mm., r 25 mm., R = S r, exactly the proportions of a Vladi- 

 vostok example. In the type, from the northeast coast of tho main islund of Japan, 

 R equals S.8 r. 



The abactinal integument of a dried or alcoholic specimen is a characteristic 

 blackish or very dark brown color, against which the yellowish spines and their 

 rather broad encircling cushions of pedicellariae arc in sharp contrast. The abac- 

 tinal spines vary somewhat in stoutness but taper from a generally cylindrical or 



■ Mem. Mus. Comp. Zool., vol. 32, p. 246, flg. 205. 



