60 CLASS Ill. GASTEROPODA. ORDER VI. PULMOBRANCHIATA. 
newly discovered mollusk, allied to the Limax or common slug ; but in- 
stead of having its shell inserted near the neck, it is situated about the 
middle of the back, enclosed in a small fleshy scutellum as in that genus. 
It may be described as being internal, somewhat spoon-shaped, enclosed 
within a fleshy shield situated towards the middle of the animal, and co- 
vered with a horny epidermis ; the spire is very short, sometimes papil- 
liform, and is contracted at the base; the aperture of the spire is very 
small ; the outer lip is somewhat irregular, and widely expanded. 
Example. 
Pl. CLIX. Fig. 1 to 3. 
PARMACELLA CALYCULATA, Sowerby, Genera of Shells, No. 13. D’Or- 
bigny, Moll. des Iles Canaries, p. 50. pl. 1. fig. 1 to 12. 
Testacellus ambiguus, De Férussac. 
Cryptella ambigua, D’Orbigny. 
Cryptella Canariensis, Webb and Berthelot. 
LIMAX, Linneus. 
Testa interna, subirregularis, subquadrata, planulata, calcareo-crystallina, 
in scutello antico inserta ; epidermide tenui, ultra margines laterales 
paululum reflexa ; vertice subretuso ; spira nulla. 
The Limaces or garden slugs, a genus of mollusks with which most 
people are familiar, appear to have been mentioned in the earliest records 
of natural history ; but the discovery of their being sometimes provided 
with an internal shell is comparatively of recent date. This shell is in- 
serted within a fleshy scutellum or shield upon the back of the neck, and 
may be described as being rather irregular, nearly square, smooth, and 
of a calcareo-crystalline composition, enclosed within a fleshy shield to- 
wards the anterior part of the animal ; it is covered with a thin epidermis 
