THE COLOURS OF THE DISK. 169 



reaching about half-round. (Fig. 4.) These bands 

 are very characteristic ; they are perfectly well-defined 

 and contrast strongly with the olive ground, which 

 approaches to black on this side : some of the bands 

 are occasionally divided into two narrower ones by a 

 crossing dark line : they are not set at quite regular 

 intervals, nor are they of equal breadth. The inner- 

 most two rows of tentacles, without losing the olive 

 and white hues which distinguish the others, are suf- 

 fused with a rich purple glow, which greatly adds to 

 the beauty of the animal. 



The oral disk is sometimes of a fine sienna-brown, 

 marked with bands of blueish gray, proceeding from 

 the base of the inmost tentacles, and tapering to a 

 point at the mouth, towards which they converge. 

 The brown hue of the disk becomes yellow-olive, or 

 a fine green, immediately around the mouth, which is 

 prominent. The lips are wrinkled, whitish, marked 

 at the two opposite points of the long diameter with a 

 tubercle, the summit of which is rose-red ; this is 

 constant ; the tubercle is the termination of a ridge 

 proceeding fi'om the corresponding tentacle on each 

 side. The disk is more generally variegated in a pretty 

 manner with black, scarlet, faAvn-colour, green and 

 white, the hues arranged in divergent stripes, and 

 running out between the bases of the inmost tentacles 

 in a starry pattern. (Figs. 2 and 3.) 



My largest specimen was ordinarily, when contract- 

 ed, a hemisphere of Ij inch in diameter, but when 

 much annoyed it would shrink to the dimensions of a 

 cherry. When expanded it was about two inches in 

 diameter, and about one inch high. In the darkness, 



Q 



