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. xi. p. 184, t. 12. 

 f. 3, 4. P. membranaceus, R & H. iii. p. 558, pi. cxiv. P. 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 pallia! 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. 



