Amphiura abernethyi sp. nov. (Figures 1–4.)

Dimensions.—Holotype: R. 140mm.; r, 7 mm.; ratio R/r, 20. The dozen or so syntypes arc fragmentary, but suggest that the data given for the holotype are generally true. The holotype is complete.

Colour: Bright orange in life, fading to pale grey in alcohol or after drying.

Disc: Form pentagonal, constricted in the interradii. Aboral surface covered by numerous closely imbricating small scales, among which the original embryonic page 2

Amphiura abernethyi sp.nov.

Fig. 1: Aboral aspect. Fig. 2: Adoral aspect.

Fig. 3: Lateral aspect of arm, near base. Fig. 4: Arrangement of spines on lateral arm-plate.

Abbreviations: D, upper arm-plate. D-C, dorso-central primary plate.- G.C., genital plate. I-R.1, first inter-radial primary plate. I-R.2, second inter-radial primary plate. L, lateral arm-plate. L.S., lowermost arm-spine. N, naked area of disc dermis. O.P., adoral plate. O.S., oral shield. R, radial primary plate. R.S., radial shield. V, lower arm-plate.

page 3 primary plates (the dorso-central, radials, first and second inter-radials) remain distinguishable in the central region. The primary plates are widely separated by intervening scaled areas in the adult. Radial shields prominent, about five times as long as broad, widest distally, attenuated proximally, reaching from near the periphery to a point about midway to the centre of the disc. Radial shields widely separated save at their distal extremities, the intervening area between them occupied by a mosaic of about 30 irregularly polygonal platelets, of uneven sizes, which do not imbricate. The proximal abradial borders of the radial shields are partly concealed by imbricating plates of the general disc scalation. Adoral surface incompletely scaled, the dermis being almost naked save for the peripheral part and the margins of the genital clefts. The genital clefts extend almost to the periphery of the disc. Oral shields spearhead-shaped, longer than broad, with an acute angle within. Adoral plates broader without than within, proximally contiguous. The inner and outer pairs of oral papillae larger than the intermediate pair.

Arms: Long and slender, tapering to fine extremities .Upper arm-plates elliptical, their long axes transverse, about three times as broad as long, the distal border of each slightly overlapping upon the proximal border of the next plate. The most proximal plate of the upper series reduced in size, partly obscured by the disc margin. Lateral plates meeting neither above nor below, the more proximal ones bearing five arm-spines, of which the lowermost is directed distad, parallel to the long axis of the arm, the other directed outwards, the second lowermost being the longest. Lower arm-plates five-sided, yet mainly sub-rectangular in outline, owing to the fact that the two disto-lateral angles are blunt right-angles, whilst the proximal angle is exceedingly obtuse; the distal border of each very weakly concave, and weakly imbricating over the proximal angle of the next plate. Tentacle scales two, one attached to the lower arm-plate, the other to the lateral plate.

Holotype; In the museum of the Department of Zoology, Victoria University College, Wellington.

Type Locality: Off Cape Campbell, Cook Strait, New Zealand; trawled from 50 fathoms.

It may be noted that no young were seen in the bursae of dissected specimens, so that the species may provisionally be regarded as oviparous. It seems unlikely that this species could be merely a larger form of Amphiura norae (as might be concluded from the fact that it has one more spine on the lateral plates, and more mosaic platelets between the radial shields); the fact that the radial shields are more slender than in the smaller A. norae. and the distinctive arrangement of the spines of the arm, both point to the conclusion that A. abernethyi is a different species. It appears to be common at the type locality, though it has not been taken at any other point. A. norae was originally described from off Cape Kidnappers, and has not with certainty been taken since.