The animal of Natica, 13-19, has a lobe on the upper part of the foot, reflected over the shell in front, and another lobe behind. The shells of Laminaria, 23, 24, are completely enveloped in similar lobes.
The shells of Odostomia are known by a fold in the inner lip of the aperture.
Two Tritons, 1, 2, are admitted for the first time as British, on what we consider fair evidence, although only two or three specimens have been taken off Guernsey. One of T. nodiferus was incrusted by a truly British Lepralia. Murex, 3, is now familiar as an aquarian, as well as Purpura, 5. A milky secretion found in the head turns purple when exposed, and gives the celebrated purple dye. Buccinum, 7-13, includes the common "Whelk," 8. Fusus Berniciensis, 14, is among the rarest and most beautiful of our British shells.
Nassa reticulata, 3, is a favourite inhabitant of the tank; it burrows in search of food among the pebbles, elevating its siphon above the surface. Mangelia, 4-26, has a similar long siphon. The shell of Erato, 27, is wrapped in the lobes of the animal's mantle, as is also that of Cyprea, 28, the latter presenting a beautiful object.
After Tornatella, 1, and Ovula, 2, 3, come Bullidæ, 4-27, including several genera differing remarkably in the shape and disposition of the lobes of their mantles, which in some instances, as in Philine, 20-25, cover the shell. The stomach of Scapander, 26, 27, is a remarkable kind of mill, composed of two bones, between which the food is ground. The shells of Aplysia, 28, and Pleurotranchus, 29, 30, are quite internal. Spirula, 31, belonging to the Cephalopodous or Cuttlefish tribe, is only introduced doubtfully, as there is no proof of the species living in our seas.