234 VELUTINID^. 



Genus I. LAMEL'LARIA*, Montagu. PI. III. f. 6. 



BODY depressed : mantle shield-like, completely enveloping 

 and concealing the shell : snout small. 



SHELL internal, white, and very thin : epidermis filmy. 



This resembles a Doris (one of the sea-slugs) in ap- 

 pearance; and no one who is unacquainted with the 

 varied structure of the Mollusca would suspect that the 

 soft body of the Lamellaria had an internal spiral shell 

 to protect its vital organs. It usually inhabits the 

 lowest margin of the littoral zone, but is sometimes 

 found in very deep water, 



" Lying with simple shells." 



The anatomy of the genus has been most carefully 

 worked out by Dr. Bergh of Copenhagen. 



Lamellaria, as a genus, was instituted by Montagu 

 (Trans. Linn. Soc. xi. pt. 2. p. 184), and divided into 

 two sections, the former being represented by Pleuro- 

 branchus membranaceus, and the latter by L. perspicua. 

 The genus Pleurobranchus having been afterwards esta- 

 blished by Cuvier, Menke in his ' Synopsis ' restricted 

 the present genus to the species comprised in Montagu's 

 second section. It forms part of the genus Sigaretus of 

 Cuvier, and is the Coriocella of De Blaiiiville. Leach 

 called it Marsenia, H. & A. Adams Cryptocella ; Gray 

 made out of it three genera, viz. Ermea for L. perspicua, 

 Lamellaria (which he placed in another family with Cy- 

 praa) for L. tentaculata these, by the bye, being dif- 

 ferent sexes of the same species, and Marsenina for 

 L. prodita. Both he and Troschel consider that Lamel- 

 laria (or Marsenia) and Marsenina belong to different 

 families, their opinion being based on the differences of 



* From the plate-like or scaly shape of the mantle. 



