18 CLASS III]. GASTEROPODA. ORDER III. CERVICOBRANCHIATA. 
pressio muscularis non symmetrica, antica parte ad dextram latiore ; 
disco centrali interno plerumque fusco-vario. 
This genus was first proposed by the indefatigable naturalists of the 
ship ‘ Astrolabe,’ MM. Quoy and Gaimard, under the name of Patelloida ; 
but as this is properly a specific and not a generic appellation, we have 
been compelled to follow the less significant and unmeaning title of 
Lottia. It is not surprising that the Lottiz should have been con- 
founded with the Patelle, as they scarcely differ from them except in the 
arrangement of the branchiz ; which, instead of being disposed in sym- 
metrical order round the body, were discovered by those zealous malacolo- 
gists to be situated in a particular cavity at the back of the neck, as in the 
Fissurelle. In other respects the internal organization of the Lottiz and 
Patelle is nearly the same, and their shells are hardly distinguishable 
from each other; as a general character we may, however, notice, that 
in those of the present genus the vertex is much more nearly approximated 
to the anterior margin. 
The shell of Lottia may be described as being patellaform or dish- 
shaped, regular, and generally rather depressed ; the vertex is anterior, 
and approximates to the margin ; in some few instances it is quite mar- 
ginal. The muscular impression is not symmetrical, the anterior part of it 
being generally rather wider on the right side ; and it has been remarked 
that the internal central disc is generally of a dark or varied colour. 
Examples. 
Pl. CXXXVII. Fig. 1. 
Lorria GiIGANTEA, Gray. Sowerby, Genera of Shells, No. 42. 
Pl. CXXXVII. Fig. 2. 
Lorrta TEsTUDINARIA, Sowerby, Genera of Shells, No. 42. 
Patella testudinaria, Linnzus. 
Pl. CXXXVII. Fig. 3. 
Lorria RADIANS, Sowerby, Genera of Shells, No. 42. 
