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 



r 16 



Length of longest spine. 1*5 



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 dcplanatumfere, brachia longissima, radio stel/a majorc 

 minorem triplum quinta parte superante ; tessellce marginahs 

 admodum convexce, alternantes c. 30 ; dorsitales, tuberculis 1—4 

 minutis obsita, sola (apice brachiorum excepta) ipsum marg'mem 

 stetla formant ; area poriferce triangulares, scepe confluentes, 

 poris numerosissimis ; tubercula numerosissima mediocria obtusa 

 in nodis trabecularum, in parte centrali stella et basalt brachi- 

 orum conica vel cylindrica fere, in parte terminali brachiorum 

 crassiora, convexa, approximata, tessellasque marginales fere 

 aquanlia, series quitias in brachi is formant, media c. 30 nume- 

 runte ; tubercula 5 duplicia paullo modo majora et parum inter 

 cetera conspicua partem centralem stellce circumdant ; tessellce 

 ventrules propria tuber culif or mes, minutes, numerosa, propter 

 granula obtegentia huud conspicuce, prcetcr granula singulam 

 (prope ambulacra duplicem vel triplicem) spinam crassam ob- 

 tusam gerunt ; popillce ambulacrales triseria/ce, interna nonce 

 graciles, cetera crassa, obtusa, ternce ( rarius bina vel quaterna); 

 pedicellaria valvulata minuta rarce prope ambidacra. Hab. ad 

 oras Bengalise." 



Oreaster superbus. 



Oreaster supeibus, Mobius, 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 ap- 

 parently 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 superomaiginals bear knobbed spines, and the inferor 

 marginals till about the middle of the arm have two, whereof the 



Proc. Zool. Soc— 1884, No. VI. 6 



