326 DISCOVERY REPORTS 



A marked feature of this species, not mentioned by Koehler, is that the jaws are 

 usually distinctly sunken in the middle, there being thus five conspicuous depressions 

 round the mouth. The two specimens from St. i8o have the dorsal arm-plates un- 

 divided, and one of them has also the buccal shields entire. As they otherwise agree with 

 the remaining specimens, particularly in regard to the tentacle pores, I have no doubt 

 that they belong to the same species, O. partita. 



The species has separate sexes, and would seem not to be viviparous. There are one 

 to three gonads at each genital slit, placed interradially, and one or none adradially. The 

 ovaries contain a small number, about three to six, large yolky eggs ca. 0-3 mm. in 

 diameter. Three of the specimens contain a very remarkable, large, parasitic Crustacean, 

 probably a Copepod (} Ophioika). It does not castrate its host. On the specimens from 

 St. 182 are further found some small Gymnoblastic Hydroids, probably identical with 

 the Hydractinio vallini described by Jaderholm {Uber einige antarkiisc/ie u. subantarktische 

 Hydroiden. Arkiv for Zoologi, xvill A, No. 14, 1926, p. 2) from Ophiurolepis WalliniJ- 

 The type specimen was taken in the neighbourhood of the South Orkneys, at a depth 

 of 3195 m. 



Ophiurolepis turgida, n.sp. 



St. WS 871. I. iv. 32. 53° 16' S, 64"^ 12' W, 336-341 m. I specimen. 



Diameter of disk 10 mm., arms scarcely three times that length, rather robust. Disk 

 flat, covered with moderately large, flat scales, among which the primary plates are only 

 little prominent. Radial shields small, oval, scarcely one-third of the disk radius; they 

 are narrowly separated distally, widely divergent proximally. Ventral interradii with a 

 moderate number of rather thick plates; genital scales not very broad. Buccal shields 

 rounded with a rather acute angle within, the point of which may be separated off as a 

 separate small plate. Adoral plates narrow, slightly narrower than the jaws. Mouth 

 papillae of the usual square shape. First ventral plate large, rounded proximally, with 

 a low peak distally. The following two to three plates narrowly contiguous or nearly so ; 

 they are of the usual, nearly triangular form. Dorsal arm-plates rather broadly con- 

 tiguous, with a low, wart-like prominence distally. Lateral plates somewhat swollen, 

 carrying two small, rudimentary spines, one near the tentacle scales, the other nearer 

 the upper edge, though some distance therefrom. Tentacle pores and scales rudimentary, 

 as typical of Ophiurolepis. Genital slits very small and narrow, not proceeding beyond 

 the first lateral plate ; there are some few low, wart-like papillae along their interradial 

 edge, these papillae continuing along the sides of the arms to the edge of the disk and 

 along the outer edge of the radial shields. Colour of the single dried specimen white. 



This species appears to be the nearest related to O. anceps, Koehler, which has also 

 quite short genital slits. But the much thicker and more swollen plates of the disk and 

 arms of O. anceps prove that they cannot be identical ; the shape of the buccal shields 

 and of the first ventral arm-plate is also quite different in the two species. From 



1 A related species, Hydractinia (Stylactis) ingolfi, found on Homalophiura tessellata (Verrill), was 

 described by Dr Kramp in the report on the Hydroids of the Godthaab Expedition 1928, in Meddelelser 

 om Gronland, 79, i, 1932, p. 13: cf. Mortensen, 'Ingolf Ophiuroids, p. 92, pi. iii, fig. 17. 



