ELYSIID^. 31 



angulated, with a central black stripe, the sides of which, as 

 well as the tentacles and the area round the eyes, are yellow or 

 fawncoloured : tentacles of moderate length, linear and cylin- 

 drical ; on each side of the back near the vent is a slight ridge 

 with three or four pale tubercular spots. L. 0-2. 



Habitat : In rock-pools between tide-marks, on Chorda 

 tomentaria and Dumontia Jtliformis, Falmouth (Cocks). [Burg- 

 head, Moray Firth (Gordon).] 



Family II. ELYSIID.E, {Elysiadce) Alder and 

 Hancock. 



Without cloak or gills: sides of the body produced into 

 foliaceous lobes : tentacles 2 or 4, generally folded longitu- 

 dinally: vent dorsal or latero-dorsal : odontojphore denticulated ; 

 no jaws. 



Though the mollusks of this family have no specialized gills, 

 the expanded lobes of the body, on the internal surface of which 

 the blood-vessels are ramified, make a nearer approach to spe- 

 cialization than in other members of the group. Several 

 handsome species of the family arc found in the seas of warm 

 climates ; with us it is represented by a single species only. 



Genus ELY'SIA*, Risso. 



[PL I. f. 6.] 



Body limaciform, with the sides expanded into lobes folding 

 over the back : tentacles 2, longitudinally folded : gastro- 

 hepatic system much branched : vent latero-dorsal, in front of 

 the heart : odontophore having a single row of spines. 



This genus is the Actoion of Oken but not of De Montfort ; 

 Aphjsiopterus of Delle Chiaje is also a synonym. 



Elysia vi'ridis, Montagu. 



Lapl^sia virldis, Mont, in Linn. Trans, vii. p. 7G, pi. 7. f. 1. E. virklts, 

 F. & H. iii. p. 614, pi. CCC. f. 3. 



Body ovate-oblong, depressed, grass-green, with bright 

 * [Possibly from eXvu), to fold inwards.] 



