EOLIS ALBA. 



The elegant and graceful form of this little animal renders it extremely attractive. The 

 dorsal tentacles are peculiar. 



It was first found in Malahide Bay, where we dredged up two specimens in about four 

 fathoms water, in August, 1843. They were adhering to the common sponge, {Halichondria 

 panicea,) which is very abundant in this locality, and grows to a larger size than we have 

 elsewhere seen. It probably constitutes the chief food of this and numerous other nudibranchs 

 that were found upon it. That this species, however, is not very scrupulous in adhering to 

 such diet we have reason to know. The two individuals after travelling three hundred miles 

 by post, lived with us two or three weeks. They were very active, and glided rather quickly 

 through the water. The dorsal tentacles were generally inclined forwards and spread much 

 apart, the oral ones were arched gracefully backwards, and kept in constant motion. The 

 papillae usually lay rather close to the body, but frequently they were spread out and curved 

 in a very graceful manner. Finding that they had devoured the spawn of another Eolis kept 

 in the same glass with them, they were afterwards fed with the spawn of a Polycera, which 

 they always laid hold of with great avidity ; another proof, if any were wanting, of the carni- 

 vorous habits of this genus. They were always most active at nights. Their spawn was de- 

 posited in a slender gelatinous flattened thread forming a delicate spiral coil of seven or 

 eight volutions ; the eggs are oval, and lie three or four abreast through the whole length of 

 the thread. 



Fig. 1, 2, 3. Eolis alba, in different positions. 



4. Two of the papillae more highly magnified. 



5. Spawn. 



6. A portion of the same, showing the ova. 



(The figures in this Plate have inadvertently been reversed.) 



