"Notwithstanding the great reductions of the _Murex_ genus, it is still large, and contains very fine species. The shells have _three or more_ varices upon each whorl; those in _Ranella_ but _two_; while _Struthiolaria_ has a varix only on the right-margin. The species are numerous, and common in collections. _M. saxatilis_ is white, and zoned with rose-colour or purple. The foliations, or branches, are erect. The Rose-bush is pretty; and the wagtail, _M. motacilla_, will, doubtless, be a favourite with you, as well as the scoop, _M. haustellum_. "Notwithstanding the resemblance of the genus _Triton_ to those of _Murex_ and _Ranella_, there are permanent differences which make them distinguishable at first sight. I have already noticed the varices of the preceding genera; in _Triton_ they never form longitudinal ranges, but are alternate, few, and nearly solitary on each whorl of the spire; these varices are generally smooth and without spines.[C] _Triton variegatum_, the marine trumpet, is a large, handsome species, from the Asiatic seas. _T. lampas_ and _T. lotorium_ are common. _Triton anus_ is very remarkable. [C] Lamarck. "In the next family, _Alata_, we must notice a remarkable fact: the shells, while they are young, assume a different form to those more advanced in growth. [Sidenote: ROSTELLARIA. PTEROCERA. STROMBUS.] "The genera are three-- _Rostellaria_, } _Pterocera_, } _Strombus_, wing-shell. _Strombus_, } "In the first genus the shells are terminated below by a canal, or pointed beak; the right-margin entire, or toothed, more or less dilated with age, and having a sinus contiguous to the canal. There is a specimen from our own coast, _Rostellaria pes-pelicani_, the pelican's-foot: it was _Strombus_ of Linnæus. (Plate 7.) There are many of this species found in a fossil state. "The _Pterocera_ genus is easily known by the digitated, or fingered, appearance of the right-margin. The greater part of the species become very large. Here we find the scorpion, with seven digitations, from India; the spider, with the same number, a large and fine shell, also from India. "_Strombus_ has a short canal, the right-margin dilated with age into a simple wing, having, at the lower part, a sinus, separated from the canal at the base of the shell. "All the species are natives of hot climates; some attain a very large size, such as _S. gigas_, so frequently seen in shops, and as ornaments in a room. _S. gibbèrulus_ is a pretty little shell; the white, gibbous whorls render it remarkable; the interior of the lip is pink. _S. lineàtus_ has dark lines round the shell. _S. vittàtus_ has a very long spire; the colour is tawny, girded with white: you may easily meet with this species. [Sidenote: CASSIDARIA. CASSIS.] "The family _Purpurifera_ is composed of genera taken chiefly from the large Linnæan genus _Buccinum_. * * * * * "It is thus divided: