FAMILY 1. LIMACINEA. 59 
Family 1. LIMACINEA. 
Testa parva, aut externa, aut interna, simplex, interdum subspiralis, cor- 
por afixa, vel ad partem anticam, vel posticam, vel mediam. 
The family of the Limacinea are placed at the commencement of the 
great series of pulmoniferous or air-breathing mollusks, because of their 
leading characters being considered as intermediate between those of the 
Aplysia and the Helices. They may be said to resemble the former, to a 
certain extent, as regards the nature and purpose of their shell, namely, 
that of affording protection to the respiratory cavity ; and the latter alto- 
gether, in their general organization and habits. The breathing appa- 
ratus of this family varies considerably in its position: in some it is situ- 
ated at the anterior part of the body ; in others at the posterior ; and in 
others again in the middle ; whilst the shell which covers it, being exter- 
nal or internal, is either simple or spiral. 
The Limacinea are for the most part to be found buried in damp earth, 
and live upon worms and various kinds of vegetable matter ; they may 
be divided into four genera, as follows : 
PARMACELLA. TESTACELLUS. 
Limax. VITRINA. 
PARMACELLA, Cuvier. 
Testa interna, subcochleariformis, epidermide cornea induta, in scutello 
mediano inserta, spira brevissima, interdum papilliformi, basi coarc- 
tata ; spire apertura minima, labio externo subirregulari, expansis- 
simo. 
The genus Parmacella was instituted by Cuvier for the reception of a 
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