90 



15. D. OBLONGA, Alder and Hancock. 



D. oblonga, A. & H. in Ann. N. H. 1st ser. xvi. p. 314 ; and Brit. Nud. 

 Moll. fam. 1, pi. 16. f. 4, 5. 



BODY oblong, tapering behind : mantle yellowish, with brown 

 spots, covered with stout conical tubercles: dorsal tentacles 

 subclavate, stout, with short sheaths: head-veil semicircular, 

 produced in front : gills 7, rather large and close-set, sur- 

 rounded by a circle of tubercles. L. 0-5. 



HABITAT : A single specimen dredged off Berry Head (Alder). 



16. D. BILAMELLA'TA, Linne. 



D. bilamellata, Linn. S. N. p. 1083 ; A. & H. Brit. Nud. Moll. fam. 1, 

 pi. 11. 



BODY elliptical : mantle dull white, mottled and blotched 

 with brown in a longitudinal direction, forming a faint band 

 down the centre of the back, and two brighter but much in- 

 terrupted bands down the sides ; covered with large, unequal, 

 clavate tubercles : dorsal tentacles linear, brownish : head-veil 

 broad, undulating : gills 20-29, small, brown, placed at a 

 little distance round the vent in a transversely elliptical or 

 horseshoe form, with the posterior ends curved inwards. 

 L. 0-5-1-5. 



HABITAT : This is one of the most common of our British 

 Dorides, often appearing in considerable numbers on the 

 rocky parts of the coast, especially in the north. Most plen- 

 tiful in the early spring, at which time they are spawning. 

 Two varieties occur, one so much larger than the other as 

 to have been frequently considered a distinct species. The 

 smaller variety is D. vulgaris of Leach, and the larger D. 

 Elfortiana and D. Leachii of De Blainville ; this latter variety 

 is also the D. affinis of Thompson. D. bilamellata is the D. 

 verrucosa of Pennant and Fleming, but not of Linne or Cuvier. 

 It is the D. liturata of Moller, and D. obvelata of Bouchard- 

 Chantereaux. The range of this species appears to extend 

 from the English Channel to Greenland. 



