124 OPHIUROIDEA. 



Opkiopholis gooclsiri, id. ibid. 



Arnphiura ballii, Sars, Nyt Mag. x. (1859) p. 42 ; id. Narg. Ech. 



(1861) p. 17, pi. 2. figs. 1-6; Norman, Ann. &• Mag. xv. (1865) 



p. 109. 

 Ophiocnida ballii, Lyman, Cat. Mm. C. Z. i. (1865) p. 12. 

 Ophiactis ballii, Lyman, Chall. Rep. (1882) p. 121 ; Hoyle, Proc. 



Roy. Soc. Ed. xii. (1884) p. 718; id. Proc. R. Phys. Soc. Ed. viii 



(1885) p. 143. 



A small species, with fairly stout, moderately long arms. Disk- 

 scales subequal, regularly imbricating, sometimes spiny. Radial 

 shields small, wider without than within ; the inner apices widely 

 separated from one another. A single mouth-papilla. Four or five 

 arm-spines, two of which may be a little longer than the length of 

 the side-plate ; the side-plates nearly meet in the middle line above, 

 and the upper arm-plates are therefore very much wider along their 

 distal than their proximal edge ; lower arm-plates cordiform, with 

 a rounded proximal edge. 



Colour, in spirit, white. " Disk yellowish or red, often mottled 

 with these two colours ; arms banded with red " {Norman). 



R=20 (about) ; r=3. 



Distribution. North Atlantic. 



a. East of Shetland Is., 203 frns. ' Porcupine ' Exp. (St. 74j. 



b, c. Dalkey Sound. Belfast Nat. Hist. Society. 



d. Giants' Causeway (adherent to Pinna). Belfast Nat. Hist. Society. 



Dr. Norman states that " it lives on hard ground, in deep water, 

 and has a peculiar habit, delighting to nestle in hollows and crevices 

 of stones, squeezing its disk and twisting its arms so as to conform 

 to all the irregularities of the surface to which it attaches itself." 

 To 203 frns. 



5. 0PHI0PUS. 



Ophiopus, Ljungman, (Efo. Vet.-Akad. Fbrh. 1866 (1867), p. 309 ; Ly- 

 man, Chall. Rep. Oph, (1882) p. 156. 

 Ophiaregma, San, Fork. Vid. Selsk. Christ. 1872 (1873), p. 112. 



Very near Ojihiactis, but distinguished by the absence of bursal 

 clefts. 



1. Ophiopus arcticus. 



Ophiopus arcticus, Ljungman, (Efo. Vet.-Akad. Fdrh. 1866 (1867), 

 p. 309; Lyman, Chall. Rep. Oph. (1882) p. 156; Hoyle. Proc. 

 Roy. Soc. Ed. xii. (1884) p. 720. 



Ophiaregma abyssorum, Sars, Forh. Vid. Selsk. Christ. 1872 (1873), 

 p. 112. *■ ; ' 



Disk pentagonal, with large central and five primary plates well 

 marked ; radial shields very obscure. Arms delicate, about seven 

 times the radius of the disk ; three or four short arm-spines, the 



