OCR Text |
Show 1884.] SPECIES OF OREASTER. 81 general granulation of which is rather delicate. In the adult the shield-shaped madreporic plate is covered with granules. Colour (in spirit) creamy white or white. Measurements: - R 24 *27 47 *48 84 r 16 16 5 22 23 50 Length of longest spine. 1*5 3 3*1 6 15 The two specimens whose admeasurements are marked with an asterisk were determined by M. Perrier as examples of his species N. michelini; but there can hardly be any doubt that within the limits of a millimetre or two differences may always obtain in the development of defensive spines, and the two species may well be united. Hab. W . coast Central America; Sandwich Islands. OREASTER WESTERMANNI. Oreaster westermanni, Liitken, Vidensk. Med. 1871, p. 264. " Dorsum deplanatum fere, brachia longissima, radio stell ce majore minorem triplum quinta parte superante; tessella? marginales admodum convexce, alternant.es c. 30 ; dorsuales, tuberculis 1-minutis obsitee, sola? (apice brachiorum excepta) ipsum marginem stellee formant ; areee poriferee triangulares, seepe confluentes, poris numerosissimis ; tubercula numerosissima mediocria obtusa in nodis trabecularum, in parte centrali stellee et basali brachiorum conica vet cylindrica fere, in parte terminali brachiorum crassiora, convexa, approximata, tessellasque marginales fere eequantia, series quinas in brachiis formant, media c. 30 numeraire ; tubercula 5 duplicia paul/o modo majora et parum inter cetera conspicua partem centralem stella? circumdant; tessella? ventrulcs propria tuber culifor mes, minuta, numerosa, propter granula obtegentia hand conspicuce, prater granula singulam (prope ambulacra dup/icem vel triplicem) spinam crassam ob-tusam gerunt; papilla ambulacrales triseriata, interna nona? graciles, cetera crassa, obtusa, terna? (rarius bina vel quaterna); pedicellaria valvulata minuta rara prope ambulacra. Hab. ad oras Bengaliae." OREASTER SUPERBUS. Oreaster supeibus, Mbbius, Neue Seesterne, p. 5; Abh. Geb. Naturw. Hamburg, Bd. iv. Abth. ii. The figures of Mobius show that this is a really remarkable species, on account of the knobbed character of its spines, and the apparently restricted size of the poriferous areas. It would seem that R is about equal to 4 r; the lophial line distinguished by the presence of knobbed processes, somewhat irregularly, but always closely, arranged. Some of the more proximal superomarginals bear knobbed spines, and the inferomarginals till about the middle of the arm have two, whereof the PROC. ZOOL. Soc-1884, No. VI. 6 |