( 72 ) 



( Sculibra nchi.) 



3. Crepidula. Lam. 



Shell with an oval base ; 

 the abdominal bag) con- 

 taining the viscera) on the 

 plate of the shell ; the 

 foot beneath; the head 

 and branchiae in front. 

 PI. 16, fig. 15, 16, 17. 



Shells, and the position of the heart and branchial, symmetrical. 



4. Fissurella. 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 branchiae on the fore 

 part of the back ; a bran- 

 chial comb on each side ; 

 with filaments on the sides 

 of the foot. PL 16, fig. 

 44. PI. 19, fig. 6, 7. 



5. Emarginula. Lam. 



A fissure instead of a 

 hole, for the same pur- 

 pose ; edges of the mantle 

 covering a great part of 

 the shell. PI. 16, fig. 13. 



6. SeptAria. Fer. Navi- 



celi.a. Lam. 



A moveable, angular tes- 

 taceous plate (besides the 

 shell) hidden in the back 

 of the abdominal bag. 



7. Carinaria. (1) Lam. 



A compressed, muscu- 

 lar portion under the bel- 

 ly, serving as a fin; shell 

 attached on the branchiae ; 

 a trunk ; head furnished 

 with tubercles. PI. 14. fig. 

 17. 



2 Conical lentacula. 



Eyes at the outer base 

 of the tentacula. 



Eyes on a tubercle at 

 the outer base of the ten- 

 tacula. 



2 Tentacula. 



Eyes at the base of 

 the tentacula. 



8. Calyptr^eA. Lam. 



(1) The skin of these animals is almost gelatinous, and has a layer of fibres under 

 it, which, when they are faken, contracts so much as to tear the body and let out 

 the intestines. 



