256 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



OPHIOTHKIX PROPINQUA Lyman. 



Plate 38, figs. 1, 2 ; plate 101, fig. 4. 



See for bibliography : 



Ophiothrix propinqua Koehler ('05), p. 81; ('05a), p. 184; ('07), p. 336; 

 ('07b), p. 253.— H. L. Clark ('15), p. 277. 



Localities. — Albatross station 5108 ; China Sea, off southern Luzon; 

 Corregidor Light bearing N. 39° E., 41.70 kilometers (22.5 miles) dis- 

 tant (lat. 14° 05' 05" N., long. 120° 19' 45" E.) ; 24 meters (13 

 fathoms) ; January 15, 1908 ; Co. 



One specimen (Cat. No. 41269, U.S.N.M.). 



Albatross station 5321; China Sea, in the vicinity of Formosa; 

 Ibugos Island (south end) bearing S. 89° W., 23.16 kilometers (1.25 

 miles) distant (lat. 20° 19' 30" N., long. 121° 51' 15" E.) ; 47 meters 

 (26 fathoms) ; November 9, 1908; wh. S., Co., brk. S. 



Two specimens (Cat. No. 41270, U.S.N.M.). 



Notes. — The specimen from station 5108 is in a good state of pres- 

 ervation, but the diameter of the disk is only 4 mm. ; the two others 

 are incomplete, and in a rather poor state of preservation. 



I include a photograph of the dorsal surface of the specimen from 

 station 5108 (pi. 38, fig. 1) . The upper arm plates have not quite the 

 same form as those in the specimen which I figured in 1898, which 

 came from the Andaman Islands ('98, pi. 3, fig. 20) ; the proximal 

 border is shorter than the distal, giving to these plates a pronounc- 

 edly trapezoidal shape. ^This is the form which I find in the small 

 specimens, while in the larger the proximal border is broader at the 

 base of the arms becoming narrow at some distance from the disk. 



The hook formed by the first ventral arm spine in O. propi?iqua 

 assumes a rather unexpected shape which recalls that which I de- 

 scribed in O. aspidota and in O. expedita. Behind the terminal point, 

 which is not very much developed, there are several similar, conical, 

 pointed and straight prongs, which are close together and parallel to 

 each other. The number of these prongs varies from six to nine 

 (pi. 101, fig. 4<?). The convex border of the hook often shows to- 

 ward its extremity two or three small asperities. 



The rather large tentacle scale ends in a strong point (fig. 4a). 



Ophiothrix' plana and O. propinqua show a very similar arrange 

 ment of the plates on the dorsal surface of the disk, and the resem • 

 blance is further accentuated by the fact that some specimens of O. 

 plana may bear small granules, while in O. propinqua the plates may 

 be completely unarmed. But the upper arm plates do not have the 

 same form in the two species; their distal border is very convex in 

 O. plana, while it is almost straight in O. propinqua, in which species 

 it is broader and often slightly trilobed; furthermore, the spines of 



