Clark — Two New Ophiurans from the China Sea. 15 



The under arm plates are about as long as broad with parallel sides 

 and a prominent notch in the distal border. 



Type.— -Cat. No. 38,666, U. S. N. M., from the north China Sea, col- 

 lected by William Stimpson. 



Ctenamphiura sinensis sp. nov. 



The disk is nearly circular, being only slightly flattened in the radial 

 regions, 9.5 mm. in diameter. 



The radial shields are short and broad, joined interiorly except for 

 their extreme tips, each pair forming a heart-shaped figure which is about 

 as broad as long, and about as long as the distance from its inner angle 

 to the outer border of the rosette of primary plates. 



The six primary plates are united in a central rosette which is entirely 

 surrounded by a line of much smaller plates; outside of this the disk is 

 covered with comparatively large ovoid overlapping plates, smaller, how- 

 ever, than the primary plates, which are largest in the middle third of 

 the interradial areas and decrease in size toward the radial shields ; in 

 each interradial line just beyond the series of small plates surrounding 

 the central rosette there is a single plate about as large as those of the 

 rosette, rounded trapezoidal in shape. The plates of the dorsal surface 

 are flat and not swollen. 



The interbrachial regions below are covered with very small equal cir- 

 cular strongly imbricating plates which near and at the dorsolateral 

 margin of the disk become larger, longer and more pointed, abruptly 

 defining the dorsal surface of the disk. 



The oral shields are approximately rhombic, though usually with the 

 distal sides somewhat longer than the proximal ; all the sides are slightly 

 concave. 



The side mouth shields meet within ; they are broadly crescentic with 

 broadly rounded ends ; the chord of the crescents of the two adjacent 

 shields make with each other a very broadly obtuse angle. 



The distalmost mouth papilla is circular and scale-like, similar to a 

 tentacle scale situated opposite it on the first under arm plate, but slightly 

 larger; the next is much larger though not much broader basally, and 

 conical; the apical is smaller than the central, lower, more or less 

 pointed. 



The arms decrease in width, and especially in height, noticeably in the 

 basal fourth, but very slowly from that point onward. 



The upper arm plates in the proximal half of the arm are approxi- 

 mately three times as broad as long, the lateral thirds of the distal border 

 broadly convex, the median third concave. 



Just beyond the disk the arm spines are ten or eleven in number; the 

 lowest is considerably stouter and longer than (sometimes twice as long 

 as) the others; the next is slightly longer than the following which are 

 short and approximately equal ; at the fifteenth side arm plate beyond 

 the border of the disk the number of arm spines is reduced to eight of 

 which the lowest, though stouter, is not much longer than the others; in 



