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



(Type specimen from Station 54.) Diameter of disk 6 mm. Width of arm, without 

 spines, close to disk, 1 mm. Four short, blunt mouth papillae on each side, the two at 

 the apex being largest and conical ; between them may be seen the lowest tooth, having 

 a broken edge. Mouth shields small, rounded, with a slight angle within. Side mouth 

 shields large, narrow within, where they meet ; broader without, where they curve 

 partially round the mouth shield. First under arm plate very small ; those beyond are 

 swollen, narrow, longer than broad, having the outer edge much rounded, deep 

 re-entering curves on the lateral sides, and a short, straight side within. Side arm 

 plates small, separated below, but just meeting above. Upper arm plates much broader 

 than long, transverse oval, with the inner edge nearly straight, outer edge curved, and 

 blunt angles on the lateral sides. Disk fiat, moderately thick and slightly angular, 

 covered with small, thin, irregular, overlapping scales ; there are six large, widely 

 separated primary plates, one round one in the centre, surrounded by five others broader 

 than long. Radial shields large, longer than wide, of an elongated pear-seed shape, 

 their pointed inner ends being separated by two small, angular scales. Interbrachial 

 space on the under surface covered by fine overlapping scales, smaller than those above. 

 Four arm spines standing close together on the side arm plates ; they are about as long 

 as an arm joint, and rather slender and tapering except the one next the lowest, which 

 is strongly swollen at the base. Large round pores, but no tentacle scales. Colour, 

 grey. 



Station 54.— May 27, 1873; lat. 34° 51' N., long. 63° 59' W. ; 2650 fathoms; 

 grey ooze. 



Amphiura canescens, Lym. (PI. XVII. figs. 7-9). 



Amphiura canescens, Lym., Bull. Mus. Comp. Zool., voL vi., part 2, p. 30, pi. xii. figs. 332-334, 

 1879. 



Five mouth papillae on each side, of which the three middle ones are longest ; point 

 of mouth angle occupied by the lowest tooth. Two tentacle scales. Three arm spines 

 about as long as a joint. 



(Type specimen from Station 171.) Diameter of disk 5 mm. Arms long and slender. 

 Width of arm, close to disk, without spines, 1 mm. Five stout, blunt mouth papillae 

 on either side of the mouth angle, the three middle ones being longer, broader, and 

 more flattened than the rest. One large, triangular papilla, or tooth, at apex of jaw. 

 Mouth shields broad triangular, with blunt angles and outer edge much rounded. Side 

 mouth shields long and narrow, but slightly swollen, broader without than within, 

 where they just meet. First under arm plate small, pentagonal, with an angle inward 

 and slightly re-entering curves on the lateral sides ; the other basal plates are large, 

 with outer edge curved, and wider than the inner, and with lateral sides re-enteringly 

 curved. Side arm plates not prominent, meeting neither above nor below at the base 



