3. CREPIDULA. Lan. 
Shell with an oval base ; 
the abdominal bag) con- 
taining the viscera) on the 
late of the shell ; the 
Fea beneath; the head 
and branchize in front. 
Pl. 16, fig. 15, 16, 17. 
( 72) 
(Scutibranchi.) 
Shells, and the position of the heart and branchie, symmetrical. 
4. Fissurevta. Lam. 
A conical shell on the 
middle of the back, with 
a small hole at the sum- 
mit (for the passage of the 
water for respiration) ex- 
tending to the cavity of 
the branchiz on the fore 
part of the back; a bran- 
chial comb on each side; 
with filaments on the sides 
of the foot. Pl. 46, fig. 
44. (PEAY, fiet6..7- 
5. Emarernura. Lam. 
A fissure instead of a 
hole, for the same pur- 
pose ; edges of the mantle 
covering a great part of 
the shell. Pl. 16, fig. 13. 
6. Sepragra. Fer. Navi- 
CELLA. Lan. 
A moveable, angular,tes- 
taceous plate (besides the 
shell) hidden in the back 
of the abdominal bag. 
7. Carmarra. (1) Lam. 
A compressed, muscu- 
lar portion under the bel- 
ly, serving as a fin; shell 
attached on the branchix : 
a trunk; head furnished 
beg tubercles. Pl. 14, fig. 
AV 
8. Caryerrma. Lam. 
2 Conical tentacula. 
2 Tentacula. 
Eyes at the outer base 
of the tentacula. 
Eyes on a tubercle at 
the outer base of the ten- 
tacula. 
Eyes at the base of 
the tentacula. 
(1) The skin of these animals is almost gelatinous, and has a layer of fibres under 
it, which, when they are taken, contracts so much as to tear the body and let out 
the intestines, 
