Fauna Associated with Crinoids of Tropical Coral Reef, etc. 95 



purple) and the ground colour was brown. Lastly, in one or two forms 

 almost the whole upper surface may be covered by a dark pigment. 

 Thus, is one specimen, the dorsum was a dark green, only relieved by 

 a white line down the middle, while in another, the dorsum was pur- 

 ple. These occurred on dark crinoids. 



On the whole, then, the myzostomids showed a great colour resem- 

 blance to their hosts, though (as in the preceding cases) striking excep- 

 tions occurred and, even when the colour schemes harmonised, pro- 

 tection from human sight at least was not always secured. 



GASTEROPODA. 



Two or three very small gasteropods, apparently parasitic, were 

 found on the crinoids. While one or two were colourless, one individual 

 (which occurred upon a very handsome crinoid striped red-brown and 

 yellow) was very similar in colouring to its host. The shell was per- 

 fectly transparent, but the body was red-brown, with distinct yellow 

 spots. Mr. G. C. Robson, of the British Museum, has kindly under- 

 taken the description of this individual. 



