FAMILY 1. FISSURACEA. 19 
Pl. CXXXVIL. Fig. 4. 
Lorrra ANTILLARUM, Sowerby, Genera of Shells, No. 42. 
SIPHONARIA, Sowerby. 
Testa orbiculata, patelleeformis, depresso-conica, non symmetrica, mar- 
gine basali plerumque crenata ; vertice sub-obliquo, posticé recurvo. 
Impressio muscularis anticé interrupta, latere dextro canali profunde 
imbuta. 
In the course of our observations on this class, we have mentioned that 
the whole of the Linnean Patelle were associated by early naturalists 
under the title of Lepas ; one species, however, the Patella sipho, appears 
to have been distinguished by Adanson, in his account of the mollusks of 
Senegal, by the appellation of Le Mouret. The peculiarity of the siphonal 
impression in the interior of the shell, which excited the attention of 
this acute naturalist, undoubtedly suggested to him the indication of a 
change in the organization of the animal, and by the result of subsequent 
discoveries his anticipation has been singularly verified. The breathing 
organs of the Siphonariz differ from those of the Patelle in being situated 
within a cavity at the back of the neck, and the canal or siphon is formed 
by the passage of the water for the purposes of respiration. This im- 
portant generic character was for some time overlooked ; it escaped the 
notice of both Cuvier and Lamarck ; to Sowerby we are indebted for the 
introduction of the genus Siphonaria, and to De Blainville and Quoy for 
the anatomical detail of the animal. 
With regard to the situation that the Siphonariz should occupy in the 
natural system, authors are much divided ; De Blainville associates them 
with the Umbrelle in a particular family of his Monopleurobranchiata (Pa- 
telloidea). In the present arrangement we have considered them as being 
intermediate between the simple and the fissurated Limpets, to which they 
are allied by the Lottie on one side, and the Parmophori on the other. 
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