1884.] SPECIES OF OREASTER. 71 



cellarise, for they not only cover the reticuhiting bars of the dorsal 

 ossicles, but invade also the poriferous areas ; the granules, of 

 ordinary character, are confined to the knobs and spines, the tips of 

 which, however, they do not cover. Along the lophial line the pro- 

 jections are always rather tubercular than spinous, but the five spines 

 at the angle of the apex and the central spine within are exceedingly 

 well developed and rather acutely pointed. A few rounded tubercles, 

 similar in character to those of the lophial Hue, are developed at the 

 sides of the disk. In dried specimens the disk rises up in an alto- 

 gether turriform fashion. Madreporite small, rather obscure, on one 

 of the sides of the disk. 



Colour (dried) greyish sandy. 



Hab. Indian Ocean generally. 



Measurements : — 



R 165 130 118 100 



r 62 44 46 37 



Height of disk 58 4.5 31 27 



Length of longest spine ..15 14 21 18 



It is to be observed that there are some not unimportant variations 

 in the characters of the spines : those of the lophial line are some- 

 times sharp, are not always blunt ; the apical spines appear to be 

 liable to early division into two or three secondary apices, or they 

 may give off a spur or projection, and, lastly, the processes at the 

 sides of the disk may become quite sharp. 



Oreaster hiulcus. 



Oreaster hiulcus, M. Tr. Syst. Ast. p. 48. 



The most important difference between this species and the pre- 

 ceding would appear to be the character of the granulation of tlie 

 dorsal ossicles and the much feebler development of pedicellariae. 



Mliller and Troschel, who alone (Syst. Ast. p. 48) have given a 

 satisfactory account of the species, give the habitat as the Indian 

 Ocean ; Prof. Perrier would appear to know of it only as from Zanzi- 

 bar and Mauritius. 



Oreaster hedemanni, Liitken, 



O. hedemanni, Liitken, Vidensk- Med. 1871, p. 263. 



" Dorsum sat altum, brachia triangularia, mediocria, acuta ; radius 

 stellce major minorem duplum et dimidium cequat ; tesseUe mar- 

 ginules utrinrpee c. 1 5, dorsales ventralibus magnitudine aqnales, 

 parte externa brachiorum forsan excepta hand alternantes et in 

 peripheritt stellce formanda ceqvaliter participes ; nonnullce {dor- 

 sales sc. 5, venirales 5-G, ad angulos stellce slice, nee nan 1 vel 2 

 versus apices brachiorum locum tenentes) tubercula minuta gerunt; 

 area poriferce regulares, sejunctce, ports numeru mediocri, 

 juxta tesselas marginales maximce ; tubercula dorsualia qui?ique 

 sat magna apice nuda, spatiis diametros busales cequantibus inter 

 se separata, tuberculum centrale mediocri circumdant ; series fere 



