u 
}:OLLUSCA. 
PlIYLLlDIA, C'VV. 
7'he mantle naked, usually coriaceous, and without any shell; the 
mouth, a small proboscis, each side of which is furnished with a ten- 
taculiim ; two others project from above two small cavities in the 
mantle. The anus is on the hind part of the mantle, and the genital 
orifices forward, under the right side ; the heart near the middle of 
the back ; the stomach simple and membranous, and the intestine 
short. 
Several species inhabit the Indian Ocean*. 
Diphyllidia, C'uv. 
The branchiae similar to those of the Phyllidiae, but the posterior 
part of the mantle more pointed ; on each side of the semicircular 
head a pointed tentaculum and a slight tubercle ; the anus on the 
right sidef. 
ORDER IV. 
TECTIBRANCHIATA J. 
Have the branchiae attached along the right side or on the back, 
in the form of leaflets, 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 are approximated to the 
Pectinibranchiata by the form of the organs of respiration, and like 
them inhabit the ocean; but they are all hermaphrodites like the 
Nudibranchiata and the Pulmonea. 
Pleurobarchus, Cuv. 
Have the body equally overl pped by the mantle and by the foot, as 
if it were between two shields. In some species a little oval calca- 
reous lamina is contained in the mantle, and a homy one in that of 
others; the mantle is emarginated above the head. The branchiae 
* Phyllidia triUneata, Seb., HI, i, 16; Cuv., Ann. dii Mus., Y, xviii, 1 ; and 
Zool., Yoy. Freycin., pi. 87, f. 7 — 10 ; Ph. ocellata, Cuv., Ib. 7 ; — Ph. pustulosa, 
Id. Ib. 8, and some new species. 
p Diphyllidia Bruymansii, Cuv. ; — Diphyll. lineata, Otto., Nov. Act. Nat. Cur., 
X, vii, or Pleuro-phyllidia, Meckel., Germ. Archiv., YIII, p. 190, pi. ii, delle 
Chinie, Mem., X, 12. 
N.B. The Linguelle of Elfort, Blainv., Malac., pi. xlvii, f. 2, does not appear to 
differ from our first species. 
M. de Blainville has given to this order the name of Monoulkukobiian- 
CHIATA. 
