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



one at the angle of the mouth slit ; they are pentagonal, with an angle inward ; lateral 

 and inner lateral sides straight ; outer side slightly curved. Tentacle scales on second 

 and third plates small, circular, and situated at the inner corners. Side arm plates 

 swollen, forming the entire covering of the arm beyond the last under arm plate, with 

 the exception of minute upper arm plates, which are triangular, with an angle within. 

 Disk covered with closely soldered plates ; in the centre of the upper surface is a 

 pentagonal plate, surrounded by five rudely hexagonal, which are connected with the 

 radial shields by plates somewhat longer than broad, between each pair of which are large 

 angular scales Eadial shields shaped like a rounded pear seed, much swollen, touching 

 at their middle point, but diverging outward and inward, separated on either side of 

 the point of contact by a small triangular scale ; on the interbrachial disk margin is an 

 angular, much swollen plate, joining three of similar character, which, with the genital 

 scales, cover the under surface of the interbrachial space ; at the base of the arm above 

 are three small rounded scales. Arm spines two, minute, blunt, and set low down on 

 the edge of the side arm plate. Colour in alcohol, white. 

 Amboyna ; 100 fathoms. 



Opkiomusiv/m lunare, Lym. (PI. I. figs. 13-16). 



Ophiomusium lunare, Isfw.., Bull. Mus. Cornp. Zool., vol. v., part 7, p. 116, pi. i. figs. 4-6, 

 1878. 



Most of the lower interbrachial space outside the mouth shield is occupied by broad 

 genital scales and a great central plate. No under arm plates beyond the third. Two 

 minute arm spines set back from edge of side arm plate. Only one lower interbrachial 

 plate. No upper arm plates beyond second. 



(Type specimen from Station 219.) Diameter of disk 7 mm. Width of arm, without 

 spines, close to disk 1*5 mm. Length of arm about 20 mm. Mouth papillae seven on 

 each side, with one, somewhat larger than the rest, at the angle of the jaw. Mouth shields 

 large, pentagonal, with an acute angle within, and outer side straight ; length to breadth 

 1 "5 : 1 . Side mouth shields large, long triangular ; sides slightly curved, with narrow ends 

 touching within. Genital scales long, with interbrachial side curved, starting at the inner 

 corner of the genital opening and touching the radial shields with their outer ends. Under 

 arm plates pentagonal, with an angle inward, and outer side slightly curved ; there are 

 only two besides the small one at the outer end of mouth slit. Side arm plates thick, 

 composing the entire covering of the arm, with the exception of the minute triangular 

 upper arm plate, which has an angle inward, and outer side curved, and disappears on the 

 second or third joint. The disk is rather flat, covered with microscopically tuberculated 

 plates, well soldered together ; the margin is occupied by one large plate, touching the 

 radial shields on either side, and extending below to the mouth shields ; the centre is 



