152 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the arm plates have the distal border slightly notched. These dif- 

 ferences are entirely secondary, and the two indubitably belong to 

 the same species. 



The type of A. agitato, was dredged in 6 08' N. latitude and 121 

 19' E. longitude, at a depth of 275 meters (153 fathoms). 



AMPHIURA AMBIGUA Kochlcr. 



Plate 69, figs. 5, 6 ; plate 96, fig. 3. 



Amphiura ambigua KCEHLEB ('05), p. 39, pi. 4, figs. 9-1]. H. L. CLARK 

 ('15) ? p. 233. 



Locality. Albatross station 5158; Sulu (Jolo) Archipelago, Tawi 

 Tawi Group; Tonakta Island (N.) bearing N. 89 W., 3.52 kilometers 

 (1.9 miles) distant (lat. 5 12' 00" N., long. 119 54' 30" E.) ; 22 

 meters (12 fathoms) ; February 21, 1908; crs. S., Sh. 



One specimen (Cat. No. 41162, U.S.N.M.). 



Notes. I described this species from two specimens found by the 

 Siboga in the Jolo Archipelago at a depth of 13 meters (7 fathoms), 

 and these two were of very small size, the diameter of the disk meas- 

 uring respectively 2 mm. and 3 mm. In the Albatross specimen the 

 diameter of the disk is also 3 mm. The third and fourth arm spines, 

 sometimes even the second, always show the little hook directed pos- 

 teriorly which occurs at their extremity, and Avhich I pointed out in 

 my original description, I give here a photograph of the ventral 

 surface of the specimen, and of one of the arms, more enlarged (pi. 

 69, figs. 5, 6), as well as figures of some of the arm spines seen under 

 the microscope (pi. 96, fig. 3). 



AMPHIURA COMMUTATA, new species. 



Plate 66, figs. 1, 2, 3 ; plate 96, fig. 6. 



Locality. Hakodate, Japan. 



One hundred and sixty-two specimens (Cat. No. 41174; typo. Cat. 

 41175, U.S.N.M.). 



Description. In the two larger specimens the diameter of the disk 

 is 6 mm. ; the arms are from 35 mm. to 38 mm. in length. 



The disk is rounded. The dorsal surface is covered with numerous 

 small, subequal, rounded, and imbricated plates, a little larger in the 

 vicinity of the radial shields, and becoming a little smaller on the 

 periphery of the disk. Six primary plates may be made out which 

 are very rounded, and all of the same size; but they are scarcely 

 larger than the plates adjoining the radial shields; the five radials 

 are separated from the dorso-central by three or four rows of plates. 

 The radial shields are triangular, two and a half times as long as 

 broad, very close together or in contact outwardly, and rather strongly 

 divergent inwardly, where they are separated by three or four rows 



