CLARK: BRITTLE-STARS. 303 



Ophiactis PTEROPOMA. 

 H. L. Clark, 1911. Bull. 75 U. S. N. M., p. 134, fig. 50. 



The only known localities for this species are on the coasts of Japan, 

 in 191-253 fms. 



Ophiactis delicata. 

 H. L. Clark, 1915. Mem. M. C. Z., 25, p. 260, pi. 11, fig. 9, 10. 



The unique holotype of this species was taken at the Murray Islands, 

 Torres Strait, apparently commensal on a comatulid. 



Ophiactis ballii. 



Ophiocoma ballii Thomson, 1840. Ann. nat. hist., 5, p. 99. 

 Ophiactis ballii Liitken, 1859. Add. ad hist. Oph., pt. 2, p. 126. 

 Amphiura ballii Sars, 1861. Ov. Norges Ech., pi. 2, fig. 1-6. 



This long-known species is found about the coasts of the British 

 Isles and Scandinavia, down to a depth of 203 fms. 



Ophiactis lymani. 

 Ljimgman, 1871. Ofv. Kongl. vet.-akad. Forh., 28, p. 629. 



Plate 4, fig. 5, 6. 



Except for two specimens from near the Cape Verde Islands, re- 

 corded as 0. lymani by Koehler, this species has hitherto been known 

 only from the original specimen, from Salt Island, Virgin Islands, in 

 30-40 fms. It was therefore a matter of much interest to find it 

 common in coralline Algae in Buccoo Bay, Tobago, in April, 1916. 

 None of the specimens taken is larger than Ljungman's type and all 

 agree well with his description. In fife the color is distinctly grayish, 

 not green as in 0. savignyi, and the arms are plainly banded with 

 darker gray or with dull red. The gray of disk and arms is not 

 uniform but variegated with lighter and darker shades. The most 

 distinctive feature of the coloration is a dusky spot on the upper side 

 of two or three of the upper arm-spines in each series. This spot, 

 referred to by Ljungman, is usually very evident but it is sometimes 

 faint and occasionally seems to be wanting. It is very faint in a 

 specimen from Fairyland Bay, Bermuda, recorded in Mem. M. C. Z., 



