63 
lysiana and Limacina, the four remaining fa- R00IV1 V1IT 
miliesofthe Gasteropoda. The genera of the Nat. hist. 
Calyptracea are, Parmophorus, or Thracian shield 
shell, Emarginula, Fissurella, Pileopsis, Calyp- 
traea, Crepidula, and Ancylus. The Bullaeana 
contain the Bullaea aperta, (Bulla aperta. Lin.) 
and several species of the genus Bulla. Laplysia 
and Dolabella are the genera of the next family. 
The shell of the former is a small cartilaginous 
scutcheon, which adheres to the posterior part of 
the back of the animal : that of the latter is 
wholly internal. The genera of the family Li- 
macina are, Parmacella, an internal shell, very 
rarely met with ; Limax (the Slug), whose shelf, 
a small testaceous lamina, is contained in a fleshy 
or coriaceous scutcheon, attached to the fore part 
of the back of the animal;—Testacella, and Vi- 
trina. The shells of the two last genera are ex¬ 
ternal. 
Order 3. Trachelipoda. The family Coli- 
macea, contains the genus Helix, a part of the 
numerous species of which are in this compart¬ 
ment 
(Table 18.) Helix continued, together with 
the genera Caracolla, Anostoma, Helicina,Pupa, 
Clausilia, and Bulimus. 
(Table 19.) The four remaining genera of 
the Colimacea, viz. Achatina, Succinea, Au¬ 
ricula, and Cyclostoma. 
(Table 20.) The families Melaniana, Pe¬ 
ristomata, and part of the Neritacea. The 
genera of the first are Melania, Melanopsis and 
Pi re n a : 
