146 DISCOVERY REPORTS 



Spine is therefore not characteristic; nor is the number of adambulacral spines 2, as 

 might be inferred from Koehler's description. The prevalent number is 3, in a sUghtly 

 obHque transverse series, as in specimen B ; or a small fourth spine may stand aborad to 

 the median or to the outermost spine. 



Koehler states (1920, p. 132) that on the actinal interradial areas of charcoti the 

 spinelets are more developed (developpe) than in antarcticus and are sometimes co- 

 ordinated into small groups ; that they have therefore undergone less degeneration than 

 in antarcticus. The individual spines are probably larger in charcoti but Koehler's com- 

 parative figure oi antarcticus (1912, pi. 3, fig. i) shows more numerous actinal spinelets 

 than in charcoti, and even a slight grouping is indicated. In small specimens of antarc- 

 ticus the spinelets are regularly disposed in small, slightly spaced groups of 2 or 3. In 

 each of the 3 specimens of charcoti the small groups of 2 or 3 spinelets are very definite, 

 well spaced. In specimens A and C those groups near the furrow function as primitive 

 spiniform pedicellariae. In such groups the spinelets are usually slightly curved toward 

 each other. 



In large specimens the abactinal paxillae are well spaced and in specimen A are sub- 

 merged in the myriad folds of the highly rugose glandular skin; in specimen C the 

 spinelets extend slightly above this skin as in Koehler's figure (pi. 2, fig. 9). On the 

 lateral part of the abactinal area, deeper transverse channels resolve themselves from the 

 maze of intricate folds to continue actinally between the marginal plates and across the 

 actinal area, disappearing between the combs of adambulacral spines. 



Although the tube-feet are large, they are not crowded as in aurorae and preserve an 

 approximate biserial arrangement. 



Specimen B, having R 51 mm., has well-developed subspherical ovaries. 



Colour note, specimen C. Pale yellow with red interradial streaks on interradii and a 

 few vertical red streaks on sides of arms. 



Type locality. Petermann Island, Graham Land coast. 



Distribution, South Georgia and Petermann Island, low tide to 235 m. 



Perknaster aurorae (Koehler) 

 (Fig. C, i-ic, 2-2fl, 3-3 rf; Plate 7, fig. 2) 

 Cryaster aurorae Koehler, 1920, p. 120, pi. 27, figs. 1-3, 5, 6; pi. 28, figs, i-ii; pi. 29, figs. 2-6; 

 pi. 30, figs. 2-5; pi. 75, fig. 1.-1923. P- 73- 

 St. 366. Four cables south of Cook Island, South Sandwich Islands, 77-152 m., i specimen. 

 St. 370. Two miles north-east of Bristol Island, South Sandwich Islands, 18-80 m., 2 specimens. 

 St. 371. One mile east of Montagu Island, South Sandwich Islands, 99-161 m., 9 specimens. 

 St. MS 71. East Cumberland Bay, South Georgia, 110-60 m., i specimen (see note below). 



Perknaster aurorae diflters from all other forms in having broader ambulacra! furrows, 

 in which the more numerous, larger podia are crowded out of the strictly biserial 

 arrangement. Even in specimens as small as the example of P. fusctis this crowding is 

 conspicuous and contrasts very sharply with the condition in fuscus where the furrow is 

 so narrow that the furrow spinelets of opposite margins interlock. In every specimen of 



