OPHIOLKPIDAE 343 



main flat, simple. Mouth papillae usually three to each side of jaw, of the common type. 

 First ventral plate triangular, conspicuously broader than the following ones, which are 

 of the shape usual in this genus ; the three or four proximal ones are contiguous. Dorsal 

 arm plates contiguous in the proximal part of the arms, not much swollen. Arm spines 

 three or four in the proximal part of arms, short, equidistant, none of them transformed 

 into hooks. Arm comb well developed, but the papillae are short, not longer than the 

 arm spines. Papillae along the genital slits rudimentary ; the slits reach to the edge of 

 the disk. Tentacle pores large, with numerous scales or papillae, as usual in the genus. 

 Colour of preserved specimens whitish. 



The species is viviparous. Probably it is also hermaphrodite, like A. Rowetti; but this 

 I have been unable to ascertain definitely. Not thinking it desirable to spoil the type 

 specimen, the only one preserved in alcohol, I have only opened one interradius from 

 the ventral side, which showed merely the young embryos (with the skeleton just be- 

 ginning to develop) lying as in ^4. Rowetti. 



The character of the gibbous elevation of the primary radial plates and the radial 

 shields distinguishes this species markedly from A. Rowetti, as well as from the other 

 species oi Amphiopliiura known from the Antarctic seas or elsewhere. The species seems 

 the nearest related to A. Rowetti, of which it may perhaps ultimately prove to be only 

 a variety. 



Ophiomastus conveniens, Koehler 



Ophiomastus conveniens, Koehler, 1923. Swedish Antarct. Exped. Asteries et Ophiures, p. 122, 



pi. XV, figs. 5-6. 

 O. convejiiens, Grieg, 1929. Echinodermata from the Palmer Archipelago, p. 10. Sci. Results 



Norwegian Antarct. Exped., n, p. 10. 



St. 181. 12. iii. 27. Schollaert Channel, Palmer Archipelago, 160-33=; "i- ^ specimen. 



The specimen is a young one, 3 mm. in diameter of disk. It is in full accordance with 

 the description and figures given by Koehler, excepting the fact that the proximal arm 

 joints have only three spines, not four, as had Koehler's specimen. 



The genital slits have just begun to appear; they are very short, not exceeding one- 

 third the length of the first lateral plate. Whether they will be longer in the adult does 

 not appear from Koehler's description and figures, but the probability is that they 

 remain quite short. 



On Koehler's statement that the plates of the disk are covered with a very fine and 

 regular granulation it may be remarked that it is the calcareous structure of the plates 

 that is rather coarse, so as to produce a granular appearance; there are no separate 

 granules. 



No information on the sexual character of this species, whether viviparous or not, or 

 hermaphrodite or not, can be gathered from the single young specimen examined. An 

 interradius was opened, but showed nothing of the genital organs, which had evidently 

 not yet developed. 



DXII ig 



