42 CLASS GASTEROPODA. 
DIPHYLLIDIA, Cuw. 
The gills similar to those of the phyllidiz, but the posterior 
part of the mantle more pointed. On each side of the semi- 
circular head, a pointed tentaculum and a slight tubercle ; the 
anus on the right side. (Diphyllidia Brugmansi, Cuv.) 
FOURTH ORDER OF GASTEROPODA. 
TECTIBRANCHIATA. 
THE gills along the right side, or on the back, in the form of 
leaves, more or less divided, but not symmetrical: they are 
more or less covered by the mantle, in the thickness of which 
a, small shell is generally contained. They approach the pec- 
tinibranchiata in the form of the organs of respiration, and 
like them inhabit the ocean ; but they are all hermaphrodites, 
like the nudibranchiata and the pulmonaria. 
PLEUROBRANCHUS, Cuv. 
The body equally overlapped by the mantle and by the 
foot, as if it were between two shields. In some species, a 
little oval calcareous lamina is contained in the mantle, and a 
horny one in that of others; the mantle is emarginated above 
the head ; the gills are attached along the right side in the 
furrow, between the mantle and the foot, forming a series 
of pyramids, divided into triangular leaflets; the mouth, a 
small proboscis, is surmounted by an emarginated lip, and by 
