290 GASTEROPODES. 



SECTION II. DORIS. Formerly the whole tribe of animals, whereof 

 this group is now only an inconsiderable part, was distinguished as the 

 Doris ; and, under that name, comprehended a great number and variety 

 of species. In dismembering the Linnoean genus, a separate section was 

 reserved for the name ; though it might have been more consistent to 

 have retained it, as generally indicating the entire race. 



Body totally or partially invested by a cloak. Tentacula two, re- 

 tractile, within sockets. Branchiae concentrated, in circular arrangement 

 towards the posterior part of the back, and collectively retractile. 



1. DORIS VERRUCOSA The Warty Doris. Plate XLII. Figs. 1, 2, 3. 



Length twenty lines, breadth eight lines, thickness six lines ; figure, 

 in repose, the longitudinal section of an ellipsoid ; head a broad thick 

 flap, with a curved margin, somewhat narrower than the shoulder, or 

 anterior part of the sole ; mouth in the under surface of the head, which 

 becomes very conspicuous after death. Two tentacula, with indented 

 sides, issue from two very low sockets, almost level with the skin, 

 wherein they are retractile. The branchial apparatus, composed of 

 eleven or twelve foliaceous or pinnate organs, with the vent in the 

 centre, is situated towards the lower extremity of the back, into which it 

 is totally retractile within the body, the orifice closing over it. 



The colour of this species is extremely variable, such as would indi- 

 cate varieties, were it not for other constant features. It is pure white, 

 dark grey, mottled brown, and all intermediate shades, frequently so 

 disposed as to exhibit no imperfect resemblance of a moth. 



The warty Doris is both pelagic and littoral, and it is the most com- 

 mon of its tribe. Thirteen occurred at once between the valves of an old 

 empty shell ; and fifteen, at another time, among a moderate quantity 

 of miscellaneous collections. 



It is extremely sluggish, and seems to exist almost in constant 

 torpor ; never feeding, and very seldom crawling, in confinement. 



