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Eurygonias gen. nov.
Odontasteridae with one conspicuous, recurved, hyaline, keel-shaped median spine on the suture of each pair of mouth-plates; the form is pentagonal; the marginal plates are few, large, and prominent, increasing in size towards the apex of the rays, with one unpaired plate in both series on the medical interradial line; the abactinal intermediate plates are large, angular, forming a mesh work, arranged in longitudinal rows, and bearing large paxillae crowned with spinelets; the actinal intermediate plates are slightly imbricating, bearing groups of spines.
Eurygonias hylacanthus sp. nov.
The form is pentagonal with straight sides, much depressed, somewhat-inflated over the radial areas, with a distinct depression along the median interradial line.
R = 61 mm.; r = 51 mm.; R = 1.2r, approximately.
The supero-marginal plates are broader than long; the one on the median-interradial line is triangular, with rounded angles; the 6 plates on each side of this one increase in size towards the apex of the ray, the last three being very distinctly larger than the others. Outside of these there is 1 smaller plate and 2 or 3 very much smaller ones at the apex of the ray. The marginal plates bear small, smooth, conical tubercles with minute granular papilliform spinelets between them; the outer part of each plate is without the tubercles, but with a closely packed mass or papilliform spinelets.
The sides are bare, and the sutures between the plates broad and well defined. The infero-marginal plates correspond in number, form, and armature with the supero-marginals, the only difference being that the increase in size of the plates towards the apex of the ray is somewhat more-marked than in the supero-marginals. The dorsal plates are irregular in form, tumid, and angular, forming a distinct meshwork. They carry large-club-shaped paxillae. In the middle of the disc these paxillae are irregularly-placed. There is a single row along the median radial line, and parallel rows to this on each side, with a few much smaller ones scattered here and there between the rows. The largest are at the middle of the disc and along the median radial line, and they decrease in size towards the edge of the disc and towards the median interradial line, those on the edge of the disc being very small indeed. The paxillae are covered at the top with numerous granular papilliform spinelets, closely packed together, about 100 on the largest ones, forming large hemispherical knobs. The papular areas have 3 or 4 pores each.
The plates on the oral surface are irregular in form and size, pavement-like, somewhat angular, tumid, and imbricating. They bear a closely-placed group of 7 or 8 rather long, cylindrical, granular, slightly tapering, blunt spines, with a wreath of small granular spinelets at the base; the size of the spines decreases towards the edge of the disc. There is 1 large, stout, keel-shaped, hyaline spine on each pair of oral plates, with 3–or 4 small, somewhat flattened, slightly tapering spines at the apex of the mouth-angle, a row along the edge on each side, and 2 or 3 larger ones between this row and the large median spine. The specimen is dry, and the adambulacral armature a good deal displaced, but it evidently consists of 4 or 5 rows of rather long, cylindrical, blunt spines; some of them taper-somewhat, while others are flattened and chisel-shaped. The madrepori-form
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plate is fairly large, somewhat convex, finely striated, and situated almost on a median interradial line. The skin on the dorsal surface is red, the marginal plates purplish-grey, the paxillae grey, the madreporiform plate white, and the oral surface creamy-white. When the specimen had been placed in alcohol for a short time and then dried it became brownish-grey above and yellowish-grey beneath.
The unique type specimen is at Victoria College, Wellington.
Amphiura arenaria sp. nov.
The disc is pentagonal, with only the slightest constrictions in the inter-brachial spaces; it is about 10 mm. in diameter. The arms are very long and slender, tapering towards the extremities; about 180 mm. in length, and 1.5 mm. wide near the disc without the spines.
The scaling on the dorsal surface of the disc is very irregular; on the outer sides of the radial shields and on the margins of the disc the scales are imbricating and larger than elsewhere; at the middle parts of the disc and in the interbrachial spaces remote from the margins the scales are small, roundish, and isolated, closer together in some specimens than in others. One scale in the centre is usually larger than those around it. The radial shields are very long, truncated without, where they meet, and tapering to a rounded point within; the scales between them are elliptical, isolated, and rather larger than the general scaling, being about the same size as those on the outside edges of the radial shields. The scaling on the oral surface is very fine.
Fig. 1.—Amphiura arenaria. Dorsal shields; X 9.
Fig. 2.—Amphiura arenaria. Mouth-plates; X 9.
There are 2 stout squarish mouth-papillae at the apex of the mouth - angle, and 1 rather long, rounded, cylindrical, and tapering on each side. The mouth-shields are small, oval, leaf-shaped, with a small point within and a longer one without, and the madreporiform plate is very large, irregularly round, much swollen, and very conspicuous. The side mouth-shields are rather large, triangular, with long angles and re-enteringly curved sides; they do not meet within. The under arm-plates are squarish, with rounded angles, those near the mouth being somewhat longer than broad. The upper arm-plates are broader than long, rounded within, narrowing and sometimes truncated without, except near the disc, where they are sometimes squarish. The side arm-plates bear 7 rounded, cylindrical, pointed spines near the disc decreasing in number outwards to 3 towards the extremities of the arms; the uppermost spine stands vertically on the arm. The tentacle-pores have 1 small, leaf-like scale; some have 2. Some young specimens have imbricating scales over the whole of the dorsal surface
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Amphiura arenaria Fig 1.—Dorsal View (enlarged) Fig. 2—Oral View (enlarged).
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of the disc. The colour in life of the skin on the disc is blue, and the scales reddish-brown. The arms are pale-reddish, with darker bands, the outer parts being sometimes pale-yellowish with grey bands, and the upper arm-plates have a dark reddish-brown median longitudinal stripe. Beneath the colour is pale reddish-yellow, sometimes with a purplish tinge. Dried and spirit specimens soon become pale yellowish-grey.
This species is near A. aster, but differs in the scaling of the disc and the shape of the mouth-parts.
Professor H. B. Kirk, of Victoria College, discovered this species in the sand at low water at the entrance of Porirua Harbour, on the north side, where it is fairly abundant. I went out with him in March, 1912, and we dug out a number of specimens. They lie vertically in the sand, about 4 in. to 6 in. below the surface, with 2 arms on one side of the disc and 3 on the other side. A specimen placed on the wet sand wriggled itself out of sight in a few minutes, and was about half an inch below the surface in twenty minutes.
The type specimens are in the Dominion Museum, at Wellington.