ASTEROIDEA 85 



Although this species is sharply differentiated from all others of the subgenus 

 Leptychaster , I think it is closer to kergiielenensis than to accrescens. 



It would be a matter of great interest to know the behaviour of this species and the 

 part played by the extraordinary rays. 



Type locality. Lat. 66° 55' S, long. 145° 21' E, 318 fathoms (just within Antarctic 

 Circle, north-east of Ross Sea proper). 



Distribution. Known only from type locality and St. 1660, Ross Sea. 



Leptychaster accrescens Koehler 



Leptotxchaster kergiielenensis Bell (nee Smith), 1908, p. 9. 



Leptotychaster accrescens Koehler, 1920, p. 246, pi. 52, fig. 5; pi. 53, figs. 1-3; pi. 54, figs. 2-9; 

 pi. 55, fig. i; pi. 74, fig. I.— 1923, P- 98, pl- 13. fig- 3- 



St. 42. Off mouth of Cumberland Bay, South Georgia, 120-204 m., 3 specimens, largest R 1 10 mm. 



St. 140. Stromness Harbour to Larsen Point, South Georgia, 122-135 m., green mud, stones, 

 I specimen. 



St. 148. Off Cape Saunders, South Georgia, 132-146 m., grey mud and stones, 2 specimens, 



I very large, R 235 mm. 



St. 474. One mile west of Shag Rocks, South Georgia, 199 m., i very young specimen. 



St. 1660, Ross Sea, 74° 46-4' S, 178° 23-4' E, 351 m., 3 specimens. 



St. 2467. Near Bouvet Island, 54° 24-1' S, 3° 15-2' E, 124-119 m., 3 specimens. 



St. 2563. Near Bouvet Island, 54° 23-8' S, 3° 28-4' E, 97 m., i specimen. 



Koehler has fully described and figured this species and listed the external features 

 which differ from those of Leptychaster kergiielenensis. It is in reality far removed 

 from that species. Examples oi accrescens of the size of adult kergiielenensis (i.t. R45 mm.) 

 are quite immature, the gonads being scarcely discernible. Indeed, in a specimen as 

 large as R no mm. the gonads which extend for two-thirds the length of ray are very 

 small (i April 1926) ; while in the largest example from the same region (9 January 1927) 

 the large ovaries contain fully formed eggs (R 235 mm.). 



Bell's large specimens, presumably from Victoria Land, are certainly not L. kergiie- 

 lenensis. They are either this species or L. magnificus. 



In the largest specimen, St. 148, R = 235-240 mm., r=8o mm., R=3r; br = 90 mm. 

 This is an imposing sea star. The 4-ranked tube feet are bulky, even in the contracted 

 condition being 15-20 mm. long, 7-8 mm. thick, and terminated by a convex or hemi- 

 spherical nipple, 2 mm. in diameter. If the power of extension is equal to that of young 

 specimens the tube feet can easily reach 45 mm. One tube foot is bifurcate with two 



terminal knobs. 



The adambulacral plates are distorted by the external row of tube feet so that two or 

 sometimes three angular furrow margins intervene between two external podia (and 

 correspond to the alternate, inner podium). Directly across ray from such a double 

 furrow margin is an interval ; that is, an external podium. This distortion is indicated in a 

 specimen as small as R 62 mm., and is well marked in the specimen with R no mm. 

 It is also characteristic of L. magnificus. 



The adambulacral armature of accrescens and magnificus is also similar. Both have the 



