OPHIOLEUCIDAE 345 



This species appears to be the nearest related to Ophiomusium {Ophiomiisa) ultimo. 

 Hertz (Deutsche Tiefsee-Exped., Ophiuroiden, p. 106, Taf. ix, figs. 1-3), in which the 

 arm joints also have a neck-like constriction. Unfortunately, Hertz' figures of this species 

 are not clear, but the much longer arm joints alone show that this East African species 

 (trom off Zanzibar) is quite distinct from the present South American species. 



Family OPHIOLEUCIDAE 



Ophiopyren regularis, Koehler 



(Plate VIII, fig. i) 



Ophwpyrefi regulare, Koehler, 1901. Result. A'oyage 'Belgica'. Echinides et Ophiures, p. 26, 



pi. viii, figs. 52-4. 

 O. regularis, Koehler, 1922. Austral. Antarct. Exped. Echinod. Ophiuroidea, p. 36, pi. Ixxxvi, 



figs. 1-2. 



St. 159. 21. i. 27. 53° 52' S, 36° 08' W, South Georgia, 160 m. 1 specimen. 



The single specimen of this species taken by the ' Discovery ' has a diameter of disk 

 of 8 mm., being thus the largest of the few (in all seven) specimens known. The arms are 

 all broken close to the disk, excepting one, of which a piece 8 mm. in length is preserved. 



A conspicuous feature not mentioned by Koehler is that the underside of the disk is 

 a little concave, looking, indeed, like a large sucking disk. Evidently this means that 

 the species lives attached to the surface of stones, corals and the like, such as is the case 

 with Ophiophycis gracilis, Mortensen (Echinoderms of St Helena, p. 458), and Astro- 

 phiiira (Mortensen, Echinoderms of South Africa, p. 396). The strong development of 

 the tube feet is also in accordance with the suggestion that it lives thus attached. 



The specimen having one of its interradii broken to pieces, I could examine the 

 gonads. They proved to be purely male in character ; thus it is certain that the species 

 has separate sexes — which makes it probable, but does not necessarily imply, that it is 

 not viviparous (cf. Ophiozonella falklandica). 



As appears from the figure given here, the specimen differs in some degree from the 

 description and figures given by Koehler. The buccal shields are slightly different, but 

 more so are the ventral plates ; in particular, I do not see these plates divided by a trans- 

 verse line, as shown in Koehler's drawing {op. cit., 1901, pi. viii, fig. 53). However, 

 owing to the faint calcification of the plates in this species (and in the Ophioleucids in 

 general) the outlines of the plates are difficult to make out. The tentacle scales also are 

 rather differently represented in Koehler's and in my drawings; this would, however, 

 seem to be due to some inaccuracy on Koehler's part, the photographic figure given in 

 his work of 1922 agreeing much better with the figure given here than with his figure in 

 the Belgica Ophiurids. The scales at the proximal pores may be rather difficult to dis- 

 tinguish ; they are sometimes hardly more than a raised edge, which is particularly the 

 case on the adradial side of the first pore pair. The spines are of unequal length, the 

 upper much shorter than the lower one. The granules along the edge of the disk do not 



19-2 



