KEPORT ON THE ASTEEOIPEA. 463 



Ana] aperture large, subcentral, surrounded by five or six subtubercular papillae. 



Ambulacral tube-feet, whicb are arranged in two rows, have a large, flat, fleshy 

 terminal disk. 



No pedicellarise of any kind are present. 



Remarks. — The character of the abactinal and actinal plating, the remarkable fasci- 

 culated spinulation of the abactinal plates, and the character of the armature of the 

 adambulacral plates, together with the absence of papulae on the abactinal surface, at once 

 distinguish Korethraster from all other genera at present known. The morphological 

 structure of the form has led Drs Danielssen and Koren 1 to place Korethraster in a 

 distinct family, which they established for its reception (Korethrasteridas), but although I 

 do not feel prepared to oppose that course, I hesitate for the present about followin"' it, 

 and until more is known of the anatomy of this and allied forms, I prefer to leave the 

 genus in the family Solasteridae, as classified by Perrier, placing it, however, in a sub- 

 family. 



Several starfishes dredged during the "Blake" Expedition have been referred by 

 Perrier to this genus, and were originally described 2 as representing two distinct species 

 under the names of Korethraster palmatus and Korethraster radians; the latter was 

 subsequently placed, 3 however, by its author under the name of Korethraster hispidus, 

 but so far as I can judge from the description given, and no figure, I am inclined to think 

 that this is certainly not the same as Wyville Thomson's Korethraster hispidus; and I 

 feel very great doubt indeed as to whether either of the forms belong to the genus Kore- 

 thraster at all. For the same reason, owing to insufficient description, I am reluctantly 

 compelled to place a third form, described by Perrier * under the name of Korethraster 

 setosus, in the same category of uncertainty. On these grounds I have not included the 

 forms mentioned in my consideration of the chorology of the genus Korethraster given 

 below. 



Chorology of the Genus Korethraster. 



a. Geographical distribution : — 



Atlantic : One species between the parallels of 60° and 80° N. 



Korethraster hispidus, in the Faeroe Channel, off the coast of Nor- 

 way, and south of Franz- Josef Land. 



1 Den Norske Nordhavs-Expedition, 1876-1878, Zoologi/xi. Asteroidea, 1884, p. 99. 



2 Bull. Mus. Comp. Zool. Harvard, 1881, vol. ix. No. 1, p. 12. 



3 Nouv. Archives Mus. Hist. Nat., 1884, 2e Sene, t. vi. p. 212. ' 



4 Rapport sur les Travaux de la Commission charged par M. le Ministre de l'lnstruction publique d'etudier 

 la Faune sous-marine dans les grandes profondeurs de la Mediterranee et de l'Oc^an Atlantique, par M. Alphonse 

 Milne-Edwards, Membre do Hnstitut (Extrait des Archives des Missiotis scientifiques et littcraires. Troisieme 

 se'rie. Tome neuvieme. Paris: 1S82), p. 51. 



