Dr. Johnston on Scottish Mollusca. 121 



ease, while it seems to feel its way with the oral tentacula. 

 Sometimes it will fix itself by the tail, which it has the power 

 of contracting into a sort of disc, and will thus hang with 

 the rest of the body at freedom. The branchiae readily fall off, 

 and it is then curious to see them move through the water 

 here and there like living independent worms, propelled by 

 the motions of the cilia which clothe their surfaces. The 

 spawn is deposited in summer on the under side of stones, in 

 long threads of a milk-white colour laid in circles. 



I can scarcely doubt the identity of this Eolidia with the 

 Eolide of Cuvier *, for the slight differences which may be 

 pointed out between our figures and descriptions may be rea- 

 sonably ascribed to a difference in the circumstances in which 

 they were made, — his from specimens preserved in spirits, 

 mine from the living mollusks. In the disposition of the 

 branchiae our species makes a close approximation to the ge- 

 nus Montagua of Fleming, the Cavolina of other authors ; and 

 the fact is perhaps sufficient to prove that those naturalists 

 act more judiciously who unite them in one. E. Cuvierii, 

 however, cannot be regarded as synonymous with any species 

 described by Cavolini or Montagu, although nearly affined to 

 the " Spezie di Limache" of the former f 9 and to the Doris 

 longicornis of the latter J. Like them it has the anterior an- 

 gles of the front of the foot greatly produced, so that they re- 

 semble tentacula with a slit along the inferior side, and hence 

 the species are characterized as having six tentacula ; but in 

 reality they have four only, and the prolongation of the angles 

 of the foot is observable to a lesser extent in all the genus. 



3. E.rufibranchialis, branchiae numerous, papillary, clothing 

 the sides rather irregularly, of a scarlet colour with white 

 apices ; tentacula 4. 



Eolis rufibranchialis, Johnston in Mag. Nat. Hist. v. 428. fig. 85. — Eoli- 

 dia Embletoni, Johnston in ibid. viii. 378. fig. 36. — Doris pedata? 

 Montagu in Linn. Trans, xi. 197. pi. 14. fig. 2. — Eolida pedata ? Flem. 



* E. Cuvierii of Blainville, Man. de Malacologie, p. 486, pi. 46 Ms. fig. 8. 

 is a totally distinct species, 

 f Pol. Mar. 190. tav. 7. fig. 3. 

 I Linn. Trans, ix. 107. pi. 7. fig. 1. 



