Sea-slugs 295 



but these almost exactly reproduce the stem and 

 capsules of the Hydroid. 



Embleton's iEolis (Eonhletonia pulclhra) is a more 

 minute example, being only about one-tifth of an 

 inch. It has only one pair of tentacles — the dorsal — 

 but the front of the foot spreads out into lobes ap- 

 parently to supply the place and functions of the 

 missing oral pair. The comparatively large oval 

 cerata are arranged alternately as in Tenjipes, but in 

 this case there are five on the right side and six on 

 the left. They are transparent, dotted with opaque 

 white, but the central cavity is bright red, as also is 

 the digestive track, clearly seen through the back. 

 There are two other species — E. minuta which 

 is very similar but more slender in all its parts ; 

 and E. pallida, which has a double series of 

 cerata along each side, and the tentacles closer 

 together. There is a variety (var. grayi) which has 

 adapted itself to fresh, or almost fresh, water, for it 

 is found in the Victoria Docks, London, where it 

 feeds upon the Freshwater Sponge {Cordylopltora 

 lacustris). 



The Minute iEolis (Galvina exigita) is a somewliat 

 similar species, with a double row of cerata on each 

 side and two pairs of tapering tentacles. It is found 

 upon Halecium and other Hydroids whose capsules 

 are mimicked by the form and colour of the cerata. 

 It may be colourless with white cerata, or these and 

 the tentacles may be banded with olive-green, whilst 

 patches of the same colour may be present on the 

 back. It is only about one-fifth of an inch in length. 

 There are six other species of this genus found on 

 our shores, of which the Three-coloured ^olis (G. tri- 



