186 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



A. libera (Kcehler) and A. sexradia (Duncan) — have only a single 

 one. The new species has some affinity with A. libera, from the 

 Cape Verde Islands, in which the mouth shields are elongated and 

 which possesses two tentacle scales on the pores of the first pair ; but 

 it is distinguished from it by its radial shields, which are quite in 

 contact, by the existence of a small supplementary scale on the first 

 arm segments, and also by the number of arm spines. As for A. 

 sexradia, from the Mergui Archipelago, it possesses six arms. 



Amphilimna sexradia and A. libera, as well as A. pentacantha, 

 have just been removed from the genus Amphilimna by Matsumoto, 

 who places them in his new genus Amphiacantha ('17, p. 178). The 

 question arises whether the new species discovered by the Albatross 

 should not also be placed in the genus Amphiacantha. I do not 

 think so, in spite of the presence of two tentacle scales. Matsumoto 

 has characterized the genus Amphiacantha by the very closely 

 crowded ("close-set") mouth papillae of which the outermost is 

 neither elongated nor spiniform, but short and flattened, by the 

 diverging radial shields, by the restricted number of the arm spines 

 (three or four) , and by the short, flattened and " leaf -like " tentacle 

 scales. These different characters, apart from the last, do not apply 

 to the Albatross ophiuran. 



In the genus Amphilimna, on the other hand, the mouth papillae 

 are well spaced and more or less conical, the two radial shields of 

 each pair are in contact, and the arm spines are numerous. However, 

 Matsumoto only leaves in the genus Amphilimna species with two 

 tentacle scales, and these scales are spiniform, especially the inner, or 

 adradial. By the presence of a single tentacle scale which, moreover, 

 is oval, our species differs from all the others assigned by Matsumoto 

 to the genus Amphilimna. But I believe that the significance of the 

 characters peculiar to this last genus which we find in it is much 

 greater than that of the characters diagnostic of the new genus 

 Amphiacantha. It must be noticed also that the Albatross species 

 possesses a small supplementary tentacle scale on the first arm seg- 

 ments which is somewhat spiniform. I therefore believe it necesary 

 to leave A. multispina in the genus in which I had placed it before 

 having seen Matsumoto's memoir. 



OPHIACTIS AFFINIS Duncan. 



Plate 62, fig. 6 ; plate 63, fig. 5. 



Ophiactis affinis Duncan (79), p. 469, pi. 10, fig. 23; pi. 11, fig. 24.— Lyman 

 ('82), p. 121.— KtEHLER ('98), p. 71; ('05), p. 26.— H. L. Clark ('15), p. 

 266.— Matsumoto ('17), p. 155. 



Locality. — San Juanico Strait, Samar Leyte Reefs ; April 13, 1908. 

 One specimen (Cat. No. 41052, U.S.N.M.). 



Notes. — The specimen is of small size; the diameter of the disk 

 does not exceed 4 mm., and only two of the arms are preserved. It 



