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



bones are liglit, with thin wings, and the tops of those next the disk margin have a small 

 process on the outer side. (See PL XXXVIII. figs. 6-9.) 



Ophierims valUncola, Lym. (PL XXIV. figs. 16-18 ; PL XXXVIII. figs. 6-9). 



Ophiernus vallincola, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 122, pi. v. figs. 170-172, 

 1878. 



Three small cylindrical pointed arm spines, less than half as long as an arm joint, set 

 close together and low dowTi on side arm plate ; mouth shields rounded and widely 

 separated. 



(Type specimen from Station 78.) Diameter of disk 9 mm. Length of arm about 50 

 mm. Width of arm close to disk, without spines 1'7 mm. Four small, short, rounded, 

 bead-like mouth papillae on either side of the mouth frames, and usually two at ajaex under 

 teeth, which are four in number, large and flat, with a rounded cutting edge ; besides these 

 there are two little papillee on the side mouth shield and two on the first under arm plate, 

 which may be considered scales of the second pair of mouth tentacles. Mouth shields 

 triangular, length to breadth aljout equal, with blunt angle inward, and outer corners 

 rounded. Side mouth shields short, broad without, pointed within, lying on lateral sides 

 of mouth shield, by which they seem widely separated, but the inner narrow points run 

 under the thick skin, and nearly meet within. First under arm plate triangular, with 

 inner angle truncated, lateral sides re-enteringiy curved, and outer edge rounded ; the rest 

 are narrow and rudely pentagonal, those near l^ase of arm having the inner angle trun- 

 cated, and the outer slightly curved ; inner laterals bounded by a re-entering curve ; 

 length to breadth "8 : "8. Side arm plates broad and flat, not meeting below, separated 

 above by the broad upper arm plates, which are much wider than long, and cover the 

 whole upper surface of arm, having the lateral sides nearly straight, and edge with a 

 slightly re-entering curve. Disk flat and round ; central portion covered with a thin, 

 naked, cross-'UTinkled skin ; along the margin are minute scattered granules, which, with 

 the thick skin, hide the underlying scales. Radial shields longer than broad, much 

 rounded, widely separated ; length to breadth 2 : 1'5. Lower interbrachial space covered 

 with a thin skin, on which there is a very scattered granulation. Genital openings wide, 

 extending from mouth shield to edge of disk. Genital scale not seen. Three small, 

 tapering, cylindrical arm spines, less than half as long as an arm joint, set low on the 

 outer edge of side arm plate. Two small rounded scales on the interbrachial edge of 

 each tentacle pore. Colour in alcohol, gi'eenish grey. 



This species grows to a large size ; one with a disk of 20 mm. was similar to the above, 

 except that the mouth angle was narrower and more prolonged, and bore, on each side of 

 the mouth frames, eight small, very close-set papilte. The granulation of the disk was 

 feeble ; in many specimens it is wholly wanting. The \K\iv of small mouth papilla3 under 

 the teeth is often wantino". 



O 



