THE SEA-SLUGS. 261 



the stomach, the result being that each is bright crimson 

 in colour, tipped with white above the point where the 

 branches of the stomach stop. In another light, however, 

 the crimson part suddenly flashes out into the brightest 

 blue optical colour, with a sheen like that of a bird's feather. 

 In certain lights the little animal closely resembles coralline, 

 while in others the blue tints make it stand out vividly. 

 It is a most beautiful little species, and lives well in confine- 

 ment. I have found it not infrequently at low spring tides. 

 The next species Eolis rufibranchialis may justly be 

 described as quite common, at any rate in the .Firth of 

 Forth, where I have found numbers of specimens. It 

 generally resembles the preceding species, except that the 



FIG. 76. Eolis rufibranchialis. Note the processes, or papillae, on the back, the 

 two pairs of tentacles, and the minute eyes at the base of the upper tentacles. 

 After Alder and Hancock. 



dorsal tentacles are transversely wrinkled, instead of 

 distinctly coronated, and the papillae bright red in colour, 

 with a white ring near the tips, and no trace of metallic 

 sheen. The body is white. This is a very hardy species, 

 and active in confinement. The general characters may be 

 easily made out from the figure. 



There are a great many other species of Eolis on our 

 shores, but those named are the commonest, and may serve 

 to give an idea of the general structure and habits. Those 

 who desire to pursue their observations further should 

 consult the beautiful Monograph of the British Nudi- 

 branchiate Mollusca, by Messrs. Alder and Hancock, or 

 attempt to make a journey to the Newcastle Museum to see 

 the original drawings of the last-named, which are among 

 the treasures of the collection there. 



