98 THE VOYAGE OF H.M.S. CHALLENGER. 



The description is from a specimen larger tlian the one figui'ed. 



Station 87.— July 21, 1873; lat. 25° 49' N., long. 20° 12' W. ; 1675 fathoms 

 (Wyv. Thorn.). Station 122.— September 10, 1873; lat. 9° 10' S., long. 34° 53' W. ; 

 350 fathoms; mud. Station 142.— December 18, 1873; lat. 35° 4' S., long. 18° 37' 

 E. ; 150 fathoms; .sand. 



Ophiomusium Jlahellum, Lym. (PL III. figs. 4-6). 



Ophiomusium flabellum, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 120, pi, v. figs. 

 141-143, 1878. 



Basal side arm plates very flat and wide, encroaching much on the interbrachial 

 space, and bearing stout spines on their outer edge. First under arm plate similar to 

 those beyond, and furnished with a tentacle scale. First side arm plates meeting on 

 median line of lower interbrachial space. 



Diameter of disk 3 "3 mm. Length of arm 3 "3 mm. Width of arm close to disk, 

 without spines, 1 mm. Mouth papillae closely soldered together, forming a continuous 

 line. Large triangular mouth frames. Mouth shields minute, diamond-shape. Side 

 mouth shields very large, meeting broadly within, with outer ends wide and much 

 rounded, having a re-entering curve on the lateral edge, where stands the tentacle scale. 

 First, second, and third under arm plates pentagonal, with a blunt angle within, outer 

 edge slightly curved, and lateral sides re-enteringly curved ; the second is largest of the 

 three ; the fourth and last is a minute, broad, triangular scale, without a tentacle pore. 

 The first pair of side arm plates are swollen, and of such extraordinary size as to meet 

 on the median line of the interbrachial space ; the second are smaller, and meet above 

 and below ; beyond the fourth under arm plate they form the entire covering of the 

 arm. Only two minute triangular upper arm plates, having the outer edge slightly 

 curved. Disk high and round, covered with thick, much swollen plates, whereof the 

 middle are somewhat sunken ; the central primary is pentagonal, surrounded by a row 

 of angular plates, of nearly equal size ; outside this row, in each interbrachial space, is 

 another angular plate separating the inner ends of the rather long, closely joined radial 

 shields. On the interbrachial margin is a large, much swollen boss, rising high above 

 the other disk plates, and connecting the neighbouring radial shields. On the inter- 

 brachial space of the under surface there is but one minute triangular scale, outside the 

 enormous first pair of side arm plates ; these carry on their outer edge three small blunt 

 spines, which look like marginal disk papillae ; the next pair carry only two spines ; 

 and beyond, there is only one, which is blunt and short, and carried low on the outer 

 edge of the plate. Only three pairs of tentacle pores (including the mouth tentacles), 

 each with one large rounded scale on the lateral sides of the under arm plates. Colour 

 in alcohol, very pale brown. 



