1. Chondrocidaris brevispina sp. nov. Plate I, figs. 1 and 2.
Test somewhat flattened, 54 mm. in horizontal diameter and 33 mm. high. Primary spines 40-45 mm. long. Test and small spines much as in C. gigantea, but all spines are markedly papillose, when seen under a lens. Coronal plates 6 or 7 in a column. Abactinal system 22 mm. in diameter, with the ocular plates small and apparently all exsert. Actinostome 27 mm. across. Primary spines remarkable for the greatly developed collar ; thus a primary 40 mm. long has the collar 15 mm. high and 7-5 mm. in diameter. Beyond the collar the spine attenuates to a blunt point very rapidly, but is covered with irregular outgrowths and bluntly pointed tubercles, often more or less encrusted with a sponge. No tridentate or large globiferous pedicellariae were found ; the small globiferous are very small, fairly numerous, and not peculiar.
Colour, olive-yellow, greener on secondary spines and quite green on peristome ; milled ring of primaries olive-yellow, collar dark olive, at base olive-yellow ; rest of spine coral red (as is the encrusting sponge) ; on the younger primaries the collar is distinctly dull red rather than olive.
Loyalty Islands, Lifu (Willey). This superb specimen of a very well-marked new species is labelled Phyllacanthus gigantea, and is recorded by Bell (1899, Willey's Zool. Res., pt. ii, p. 135) under that name, almost without comment. It is easily distinguished from P. gigantea by the remarkable primary spines.