10 PLEUROBRANCHID.E. 



brated 'Memoires/ which was in 1817; Montagu's 

 paper appeared two years previously. Dr. Woodward 

 detected spicula in the mantle ; this confirms the gene- 

 rally received opinion that Pleurobranchus is allied to 

 the Nudibranchs. It resembles Doris in shape. The 

 nature of its food is not known. Its alimentary system 

 is complicated^ and said to consist of no less than four 

 stomachs. 



De Blainville called it Berthella, Gray Pleurobranchia, 

 and Leach Cleantus and Oscanius. 



1. Pleurobranchus membrana'ceus*, Montagu. 



Lamellaria membranacea, Mont, in Trans. Linn. Soc. si. p. 184, t. 12. 

 f. 3, 4. P. membranaceus, F. & H. iii. p. 558, pi. cxiv. f. f. 5, and (ani- 

 mal) pi. XX. f. 3. 



Body tortoise-shaped or roundish -oval, thick, forming two 

 disks, one above and the other below — usually pale yellow, with 

 reddish-brown streaks or blotches ; but the shades of colour are 

 variable : mantle notched in front and behind, studded with 

 yellow papillae or tubercles of different sizes, " and in their 

 interstices a red-brown colour meanders in various breadths 

 and irregular blotches, interspersed with cloudings of pale 

 yellow flakes ; " the groove or space between the mantle and 

 foot is large and deep: head a thick muzzle, springing from 

 the centre of the pallial membrane, which is strongly auricled, 

 pale blue on the under surface, and sprinkled on the upper 

 with flake-white and red points : tentacles short, cloven though 

 apparently tubular, " united at their origins, but diverging to 

 their points, marked with close-set lines and snow-white dots : " 

 eyes indistinct, imbedded in the centre of the bases of the ten- 

 tacles, and therefore nearly contiguous : foot extremely flexible, 

 and probably serving for natation as well as for crawling : 

 sole pale yellow, marked with a multitude of irregular ana- 

 stomosing deeper-yellow lines : gill-plume " splendid," some- 

 what like an ostrich -feather, nearly half the length of the 

 body, floating free for about a quarter of an inch ; the leaves 

 are finely ciliated. L. 4. (Clark.) 



* Membranous. 



