ECHINODERMATA — CLARK. 539 



OPHIOMUSIUM FLABELLUM. 



Ophiomusnan flahellum, Lyman, Bull. Mus. Comp. Zool v 7 

 1S78, p.l20. ^ ' M ', 



3 specimens from Station 13. Off Cape Three Points, 41-50 

 fathoms; sticky mud and shell. 



1 specimen from Station 55. Off Crookhaven River, 11-15 

 fathoms ; sand to rock. 



It is a piece of real good fortune that the " Thetis " should 

 have taken this interesting little species, previously known from 

 only the single specimen taken by the " Challenger." On account 

 of its small size it might be easily overlooked, but once noted, its 

 peculiar specific characters would prevent any mistake in identifi- 

 cation. The "Thetis" specimens have the disc about 3 mm. in 

 diameter, and the arms 2i mm. long. Their colour is nearly white. 



OPHIACTIS RESILIENS. 



Ophiactis resiliens, Lyman, Bull. Mus. Comp. Zool., vi , 2, 1879 

 p. 36. 



9 specimens from Station 10. Off Broken Head, 28 fathoms ; 

 fine sand. 



16 specimens from Station 44, Off Coogee, 49-50 fathoms; 

 fine sand. 



1 specimen from Station 54. Within Jervis Bay, 10-11 

 fathoms ; seaweed and sand. 



1 specimen from Station 57. Off Wata Mooli, 54-59 fathoms; 

 all mud. 



This is another of the " Challenger " species which has been 

 brought to light again by the " Thetis." The series of specimens 

 ranges in diameter of disc from three to ten millimetres, and the 

 arras are six to eight times as long. Lyman^^ places this species 

 in the group in which, he says, "the number of mouth papillse 

 increases with age." In his original description he says there was 

 only one specimen in the " Challenger " collection, and it is there- 

 fore hard to understand upon what evidence he bases the state- 

 ment. The series of specimens collected by the " Thetis " reveals 

 no such increase. The number of spinelets in the interbi'achial 

 spaces varies greatly in different individuals; they are often very 

 numerous, extending well on to the disc, but sometimes they are 

 very few and scarcely to be seen from above. The arms are very 

 flat, noticeably wider at about the twelfth joint than at the base, 

 and then tapering to a long and very attenuate point. 



18 Lyman—" Chall." Report, Zool., v., 14, 1881, p. 11 3. 



