OPHIACANTHIDAE 259 



be difficult for the mother animal to get sufficient nourishment, a situation apparently 

 the more precarious since it appears that breeding goes on constantly, when once started. 

 One of the specimens from St. 175, a young one of only 2-2 mm. diameter of disk, 

 differs from the other specimens in the stumps of the disk being long and slender, re- 

 calling, as a matter of fact, the Ophiacantha paramedea of Hertz (Deutsche Sudpolar 

 Exped. Ophiuroiden, p. 39,Taf. vii, fig. 6; viii, figs. 1-2). However, a comparison with 

 young ones of O . falklandica taken out of the bursae leaves no doubt that this specimen 

 is only a newly born O. falklandica, the spines of the disk being equally long and slender 

 in the still unborn young ones. By this I do not mean to say that Ophiacantha para- 

 medea is only a young Ophiomitrella falklandica. The fact that the specimens of the 

 O. paramedea were 4-5 mm. in diameter of disk, shows that they cannot be identical with 

 O. falklandica, for specimens of the latter of this size have the same general appearance 

 as the adult. This, however, is not the place to discuss the species Ophiacantha paramedea. 



Ophiochondrus stelliger, Lyman 



Ophiochondms steUiger, Lyman, 1882. Sci. Results H.M.S. 'Challenger'. Ophiuroidea, p. 247, 



pi. xxi, figs. 13-15. 

 O.falklandicus, Koehler, 1923. Swedish Antarct. Exped. Asteries et Ophiures, p. 103, pi. xiv, 

 figs. 2-3. 

 St. WS 228. 30. vi. 28. 50° 50' S, 56° 58' W, off Falkland Islands, 229-236 m. 3 specimens. 

 St. WS 824. 19. i. 32. 52° 29' S, 58° 27' W, off Falkland Islands, 146-137 m. 2 specimens. 

 St. WS 871. I. iv. 32. 53° 16' S, 64° 12' W, off Falkland Islands, 336-341 m. i specimen. 



There is no doubt but that these specimens are identical with Koehler's O. falk- 

 landicus; but it is equally certain that this latter is again identical with Lyman's O. 

 stelliger. That they were closely related was observed by Koehler, who, however, 

 thought them to differ, O. falklandicus having only three arm spines, of about equal 

 length, whereas O. stelliger has four, the upper one much the longest. Further, the 

 buccal shields were supposed to be different, Lyman's pi. xxi, fig. 13, showing the shape 

 of the buccal shield much broader than that oi falklandicus, as seen in pi. xiv, fig. 3, of 

 Koehler's work. Another difference of much more importance escaped the attention of 

 Koehler, viz. that the genital slits in O. stelliger are shown in Lyman's figure to be long, 

 reaching to the very edge of the disk, whereas in Koehler's species they are only half 

 that length. 



Finding, however, that in the present specimens there are on the proximal joints 

 actually four arm-spines, the upper one distinctly the longest, I strongly suspected the 

 two other differences to be due to incorrect drawing. At my request Mr Dilwyn John 

 very kindly sent me a camera sketch of the oral side of the type specimen, which shows 

 the genital slits to be short as in falklandicus and the buccal shields of exactly the same 

 shape as infalklatidicus. Thus the identity of O.falklandicus with O. stelliger is definitely 

 proved. 



From a zoogeographical point of view this identity is also acceptable, the type locality, 

 off La Plata (1080 m.), being essentially within the same region as the Falkland Islands ; 

 the species is known from only these two localities. 



