APPENDIX. 349 



nearly as long as diameter of disk, rounded at the end ; all 

 the ossicules of the back, edge and oral surface covered 

 with regular uniform rather long erect granules, forming a 

 level surface of the oval surface longest. 



The marginal ossicule narrow, erect, rounded above ; 

 ambulacral spines elongate. 



Inhab. — Port Essington. 



This species, from the length of the granules, passes 

 towards Astropecten, the elongated tubercles having much 

 the appearance of those which are called Paxilli in that 

 genus. 



Pentagonaster Dubeni, n. s. 



Body flat, five-rayed, rays two-thirds the length of the 

 diameter of the disk, rounded at the ends. 



Ossicules all convex, rounded. 



Marginal ossicules ^} large rounded, those near the end 

 of the arms largest, most convex. 



Inhab. — West Australia. 



This species differs from P. pulchellus in the marginal 

 ossicules, being more equal, and in the arms being much 

 longer, and more slender. 



The ossicules of the dorsal disk are unequal sized and 

 rather irregularly formed, those near the margin on the 

 middle of the sides are oblong and narrow, those of the 

 oral surface are more regular and not so convex, those near 

 the angles of the mouth being the largest and subtriangular. 



I have named this beautiful species in honour of M. M. 

 W. Von Diiben, who has lately published a very admirable 

 paper on the Northern species of this family. 



Tosia, Gray. 



The granules between the ossicules are deficient in the 

 dead and washed specimens. It has been thought that the 



