OPHIACTIS. 



123 



shields moderate; covering-plates of disk stout, numerous, im- 

 bricating. Arms stout, never long, with strong, solid, smooth 

 spines. 



Key to the Species. 



Two mouth-papillae 1. O. abyssicola. 



One mouth-papilla 2. 0. balli. 



1. Ophiactis abyssicola. 



p. 324 ; Lyman, L'hall. Bej). Oph. (1882) p. 122 ; id. Proc. B. Soc. 

 Ed. xi. (1882) p. 707 ; Hoi/le, op. cit. xii. (1884) pp. 710, 715, 718 ; 

 id. Proc. B. Phys. Soc. Ed. viii. (1884) p. 143. 



A rather small species, with stout scales and rather stronger arms. 

 Disk-scales very unequal in size, thickened ; many of them carry 

 stout spines. Radial shields rather large, separated each from 

 its fellow by three or four small plates ; they have an irregularly 

 straight inner and a convex outer edge. Two ruouth-papillse. 

 Three or four stoutish arm-spines, the uppermost the longest and as 

 long as the upper arm-plates ; the side-plates encroach consider- 

 ably on the upper and lower plates, both of which are much wider 

 distally than proximally; the upper arm-plate is very narrow 

 proximally. 



Colour, in spirit, white : " laete carneus seu aurantiacus, in medio 

 dorso subfusco-carneus, spinis pallidioribus " (Sars). 



r=4-5-2-5; R=22-30. 



Distribution. Coasts of Norway. 64-767 fms. 



a, b. Faeroe Channel, 542 fms. ' Porcupine ' Exp. (St. 47 a). 



c-f. Faeroe Channel, 440 fms. ' Porcupine ' Exp. (St. 51). 



y-p. Faeroe Channel, 384 fms. ' Porcupine ' Exp. (St. 52). 



q. Faeroe Channel, 345 fms. ' Porcupine ' Exp. (St. 65). 



r-w. Faeroe Channel, 458 fms. ' Porcupine ' Exp. (St. 90). 



x. East of Shetland, 203 fms * ' Porcupine ' Exp. (St. 74). 



y, z, a'-c. No loc. Wyv. Thomson Coll. 



2. Ophiactis balli. 



Ophioconia ballii, Thompson, Ann. fy May. v. (1840) p. 99 ; Forbes, 

 Brit. Star/. (1840) p. 35; Thompson, Nat. Hist. Irel. (1856) 

 p. 437. 



Ophiocoma goodsiri, Forbes, t. c. p. 57. 



Ophiolepis ballii, M.Tr.Syst. Ast. (1842) p. 97. 



Ophiolepis goodsiri, iid. ibid. 



Ophiopkolis ballii, Gray, Cat. Brit. Bad. (1848) p. 25. 



* Mr. Lyman, who named these specimens, notes that they have few or no 

 disk-spines, and have thick scales. 



