92 ASTEROIDEA. 



Slad. Echinod. Arctic Sea, (1881) p. 43 ; Sladen, Chall. Rep. Ast. 

 (1889) p. 459. 

 Chastaster borealis (n. n.), D'dben, Of v. Svensk. Ak. Fork. 1844 (1845), 

 p. 113. 



R = 3 r (nearly). 



Arms five ; spines in delicate tufts, rather widely spread or rather 

 coarser and more closely packed ; arms wide and flat ; the marginals 

 of both series with an elongated pedicle ; three or four spines on 

 each adamhulacral plate. Colour in spirit yellowish. 



Not known to grow as large as its congeners. 



Distribution. Both sides of North Atlantic ; on the East not 

 known south of Faeroe Channel ; on the West as far south as the 

 Gulf of Maine. To 605 fathoms. 



a. Faeroe Channel. 384 fms. ' Porcupine ' Exp. 



CORETHRASTERID^E {see p. 23). 



CORETHRASTER. 



Korethraster, Wyv. Thorns. Depths of the Sea, (1873) p. 120 (n. n., but 

 Jiff, of K. hispidus, sp. n.) ; Dan. ty Kor. op. cit. p. 95 ; (?) Per/: Nouv. 

 Arch. Mus. vi. (1884) p. 211 ; Slad. Chall. Ast. (1889) p. 462. 



Corethraster, v. Marenz. Denkschr. Ak. Wien, xxxv. (1878) p. 383. 



1. Corethraster hispidus. 



Corethraster hispidus, Wyv. Thorns. Depths of the Sea, (1873) p. 120, 

 fig. 15 ; v. Marenz. Denkschr. Ak. Wien, xxxv. (1878) p. 383 ; 

 Dan. Sf Kor. Norske Nordhavs Ast. (1884) p. 95, pi. xii. ; Sladen, 

 Chall. Rep. Ast. (1889) p. 464, pi. lxxx. hgs. 6-9. 



Body thick ; rays in young twice, in older forms four times as 

 long as radius of disk. Spines very long, arranged in tufts of 6-10, 

 which are united at their base. Adamhulacral spines in two rows, 

 flat and hollow. Pale yellow. 



Measurements of single British specimen : — 



R = 8'5, r=4*5 ; height =4; spines —2 mm. 



Distribution. Northern Atlantic. So far as is known from the 

 eastern side only. The species spoken of by Mr. Whiteaves (Ann. & 

 Mag. x. (1872) p. 346) is, as he informs me, Pteraster mUitaris, 

 and not, as might be supposed, Co rethraster hisjridus. 101-632 fms. 



a. Faeroe Channel, 60° 14' N., 6° 17' W., 632 fms. ' Porcupine ' Exp. 



PTERASTERID^E {see p. 23). 



Key to the Genera of Pterasteridae. 



a. Adamhulacral spines in transverse combs ; 



spines united by a web 1. Pteraster, p. 93. 



b. Adamhulacral spines not forming transverse 



combs ; spines not united by a web 2. Hymenaster, p. 94. 



