416 THE VOYAGE OF H.M.S. CHALLENGER. 



CJiorological Synopsis of the Species herein mentioned. 



1. Metrodira subulata, Gray. 



Metrodira stibulata, Gray, 1840, Ann. and Mag. Nat. Hist., vol. vi. p. 282. 

 Seytaster subulatus, Miiller and Trosehel, 1842, System der Asteriden, p. 36. 



Locality. — Station 186. In Torres Strait, off Cape York. September 8, 1874. Lat. 

 10° 30' 0" S., long. 142° 18' 0" E. Depth 8 fathoms. Coral mud. Surface tempera- 

 ture 77° -2 Fahr. 



Family Zoeoasterid^b, Sladen, 1888. 



The genus Zoroaster was originally classified by Sir Wyville Thomson 1 in the 

 Asteriidas. It was subsequently referred by Perrier 2 to the family Pedicellasteridae, 

 established by him in 1884. In the following year, 1885, it was, however, removed by 

 Perrier 3 into the new family Stichasteridse. In my opinion Zoroaster and its allies are 

 very far removed from Pedicellaster, and, although in some of their characters they 

 approach much more nearly Stichaster, I consider that the details of their structure 

 justify the establishment of an independent family. ^ 



I include in this family the genera Zoroaster, Cnemidaster, and Pholidaster. 



Genus Zoroaster, Wyville Thomson. 

 Zoroaster, Wyville Thomson, The Depths of the Sea, 1873, p. 154. 



Disk small. Rays long, narrow, tapering throughout, arched abactinally and with a 

 more or less definite median keel, tumid actinally. Interbrachial arcs acute. 



Abactinal, marginal, and actinal intermediate plates arranged in regular longitudinal 

 lines along the ray. Regular transverse series are also formed, the plates being corre- 

 spondent and ecpial in length in each series as they proceed along the ray, excepting the 

 plates in the median series, which are larger. The surface of all the plates is covered with 

 small widely-spaced granules, upon which are articulated small, papilliform, skin-covered 

 spinelets. A small robust conical spine may be borne on the plates of the median series, 



1 The Depths of the Sea, 1873, p. 154. 



2 Nouv. Archives Mus. Hid. Nat., 2e Serie, t. vi., p. 167 and p. 195. 



3 Ann. Sci. Nat. (Zool.), 1885, t. xix., art. No. 8, p. 15. 



