Fauna Associated with Crinoids of Tropical Coral Reef, etc. 91 
ECHINODERMS. 
The only echinoderms which were found associated with the crinoids 
were ophiurans, and of these only one genus (Ophiomaza) is charac- 
teristically commensal. A small species of Ophiactis, which seems 
to be as yet undescribed, and a young Ophiocoma, too small for accu- 
rate determination, were found on Comanthus annulatum, but it was 
not possible to determine whether this association was anything more 
than accidental. But of Ophiomaza a sufficient number of specimens 
was found to show that that genus is normally commensal. All the 
individuals taken were on comatulids; none were seen elsewhere. On 
Comanthus annulatum were found specimens of Ophiomaza cacaotica, 
uniformly black (or very deep purple or brown); O. cacaotica var. picta, 
prettily marked with black and white; and O. obscura, brown, hand- 
somely marked with dull yellow. In all these cases, a certain amount 
of correlation between the colour of the ophiuran and the colour of the 
host was obvious. But on a bright red Comatula purpurea was found 
a small black specimen of O. cacaotica, and of course the colour contrast 
was very striking. However, Ophiomaza was much too rare to permit 
any reliable deductions to be drawn concerning the influence of com- 
mensalism on the colouration. 
POLYCHAETA. 
Polynoé minuta Potts var. oculata var. n. 
This polychzte, which I found rather frequently on the darker vari- 
eties of Comanthus annulatum, undoubtedly comes nearest to Polynoé? 
minuta, which I described in 1910 from specimens collected by Professor 
J. Stanley Gardiner in the Maldives.* It was not stated that this form 
a : Bd c 
4s 
\ A | € 
Fic. 7.—Polynoé minuta Potts var. oculata var. n. 
A. Head and anterior part of dorsum to show colour pattern; median tentacle, 
tentacular cirri, and dorsal cirri all wanting. 8. 
B. Setz. a, dorsal; b-e, ventral. 
C. Parapodium of sixth segment. 65. 
References in text: A, B, C, X163; D, FE, 280. 
occurred upon crinoids, although the labels of the various specimens of 
P. crinoidicola, in the same collection, gave quite definite information 
*Trans. Linn. Soc., London, vol. xu, pt. 2, Polycheta of the Indian Ocean; pt. mu, The 
Palmyridz, Aphroditide, Accetide, and Sigalionide. See p. 337. 
