196 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



oblique in reference to the longitudinal axis of the arm, and this 

 groove may even bifurcate. The supplementary dorsal plates are 

 themselves also sometimes divided into two. I give here a photo- 

 graph of the dorsal surface of one of the Albatross specimens (pi. 61, 



fig- 3). 



On plate 96 as figure 14 I give some photographs of the elongated 



granules borne on the dorsal surface of the disk (d) ; the dimensions 

 of these granules vary considerably. I include also photographs of 

 the first ventral arm spine at the commencement of the arms (a) , in 

 the distal half (b) , and at the tip after it has become definitely trans- 

 formed into a hook (c). 



The type of Ophiopholis mirabilis, described by Duncan, came 

 from the Korean Sea (Dondai Bay) . H. L. Clark reports the species 

 from numerous localities in Japan (Hakodate, Doumiki Said, Ando 

 Saki, Uraga Strait, Kinkwasan Light, etc.), at depths included be- 

 tween 11.5 and 79 fathoms. Matsumoto gives various other localities, 

 and at the same time he describes the variations which he has ob- 

 served in the coloration of the living animals. 



It seems to me that Ophiopholis mirabilis is a decidedly different 

 form from O. aeuleata (Linnaeus) which must be specifically dis- 

 tinguished from it. 



OPHIOCENTEUS ACULEATUS Ljungman. 



Plate 71, figs. 1-3 ; plate 96, fig. 8. 



OpMocentnts aculeatiis Ljtjngman ('66), p. 321.— Lyman ('82), p. 167.— H. 

 L. Clark ('15), p. 268. 



Locality. — Albatross station 5302; China Sea, in the vicinity of 

 Hongkong (lat. 21° 42' 00" N., long. 114° 50' 00" E.) ; 69 meters 

 (38 fathoms) ; August 9, 1908; sft. gy. M. 



One specimen (Cat. No. 41011, U.S.N.M.). 



Notes. — Ophiocentrus aculeatus is known only from Ljungman's 

 very short diagnosis, and it does not appear to have come to light 

 since 1864. My specimen differs in some respects from Ljungman's 

 description, but I believe nevertheless that it represents the same 

 species. First of all I shall give a description of it in order to be 

 able most advantageously to make a comparison with that of the 

 Swedish author. 



The diameter of the disk, measured between the distal extremity of 

 a radial shield and the deepest part of the opposite interradial space 

 is 8 mm.; the specimen is thus larger than that of Ljungman, who 

 gives 6 mm. as the diameter of the disk; the arms reach from 75 

 mm. to 80 mm. in length. 



The disk is rather strongly excavated in the interradial spaces. 

 The dorsal surface is in a large part occupied by the radial shields, 



