338 DISCOVERY REPORTS 



Ophiocten dubium, Koehler 



Ophiocten dubium, Koehler, 1901. Result. Voyage 'Belgica'. Echinides et Ophiures, p. 20, 



pi. vi, figs. 40-1. 

 O. dubiutn, Koehler, 191 2. IF Exped. Antarct. Fran9aise. Echinodermes, p. 129. 

 O. dubium, subsp. gaussense, Hertz, 1926. Deutsche Siidpolar-Exped. Ophiuroiden, p. 15, 



Taf. ii, figs. 4-5. 



St. 170. 23. ii. 27. Off Cape Bowles, Clarence Island, 342 m. i specimen. 

 St. 190. 24. iii. 27. Bismarck Strait, Palmer Archipelago, 130 m. 2 specimens. 



These are perfectly typical specimens of this remarkable Ophiocten. The specimen 

 from St. 170 is adult, 9 mm. in diameter of disk. It is a ripe male, full of large testes; 

 this shows the species to have separate sexes and to be, in all probability, non-viviparous. 

 The specimens from St. 190 are young, 3-5 mm. in diameter of disk. 



I do not think the subspecies gaussense of Hertz valid. The character on which it is 

 based, eight arm spines, instead of nine to ten in the typical form, and somewhat longer 

 than in the latter, is quite unimportant, and no doubt subject to a good deal of variation, 

 as is usually the case in Ophiurids with numerous spines. Since only a very small 

 number of specimens of this species have as yet been recorded, twelve in all, it seems 

 unjustifiable to establish a separate subspecies on this character. 



Ophiocten bisquamatum, n.sp. 



St. 42. I. iv. 26. Off mouth of Cumberland Bay, South Georgia, 120-204 n"*- 3 specimens. 

 St. 140. 23. xii. 26. Stromness Harbour to Larsen Point, South Georgia, 122-136 m. i specimen. 

 St. 152. 17. i. 27. 53° 51' S, 36° 18' W, South Georgia, 245 m. i specimen. 



Diameter of disk of largest specimen 3-5 mm. Arms broken, but apparently not more 

 than ca. 12-15 mm. in length. The disk is flattened, but the edge is rather high, 

 rounded, not at all sharp as in most species of Ophiocten. There is usually a large, 

 circular central plate which is somewhat eccentric (one of the specimens has no central 

 plate). The disk is otherwise covered by rather large, imbricating plates, among which 

 the primary plates are not distinct. Along the edges of the plates are found some very 

 small, slightly elevated scales, like very low, nearly flat granules. The radial shields are 

 distinctly broader than long, contiguous distally or wholly separated. The disk scales on 

 the whole are exceedingly thin and delicate, looking dark (transparent) in the middle, 

 whitish along the edges, where they imbricate. The ventral interradii show only some 

 few small plates outside the large, squarish, rounded buccal shields. Mouth papillae 

 four at each side of the jaw, the proximal ones pointed. 



First ventral plate large, polygonal, with convex distal edge. The second ventral plate 

 contiguous with the first, the third nearly contiguous with the second, the following ones 

 widely separated. All the ventral plates with strongly convex distal edge. Dorsal arm- 

 plates rectangular, with outer edge convex; they are distinctly longer than broad, and 

 broadly contiguous. Three arm spines, the uppermost one the longest, only little longer 

 than an arm joint in the proximal part of the arm. Tentacle scales at the first pore pair 

 one at the adradial, three at the interradial side; the outer one of the three latter is 

 elongate, spine-like, the others more leaf-shaped. The following pores have two, some- 



