Norwich Castle Museum. cE3T 
Case I. | 
of which will be found the remainder of the Mol- 
lusca. 
The extensive Fifth Order, NUDIBRANCHIATA, 
known as the naked-gilled Molluscs, or Sea Slugs, 
being shell-less except in a very early stage of their 
existence, are not represented here; there are many 
strange and beautiful forms of these creatures both 
varied and graceful. | 
Owing to the extremely artificial arrangement 
adopted by Mr. Gwyn Jeffreys, namely, land, fresh- 
water, and marine shells, there are four families of air- 
breathing Mollusca (Pulmonobrancbiata), inhabiting 
estuaries where the water is neither fresh nor salt, 
which have been left out in thecold. The first family 
(Oncidiadze) is not represented in our collection, but 
of the second family (Assimineidee) we have both 
species, 4. grvayana, found only on the banks of the 
Thames, between Greenwich and Gravesend, and A. 
iittorina, which makes its home inside the Chesil Bank 
at Weymouth, and in a few other places. Woodward 
places both these in the family Lirorinip#. In the 
third family (Carychiadze), we have also both species 
of the only genus A/elampus, M. bidentatus and MM. 
myosotus ; they are spindle-shaped shells, the former 
frequenting ground between tidemarks, and the latter 
mud-flats and salt-marshes. ‘These Woodward places 
in the family Avuricutip#, Of the fourth family 
(Otinidz) we have no representative. 
Of the class PTEROPODA, the small wing-footed 
Molluscs, inhabiting the open sea, we have already 
spoken at p. 115, as also of the CEPHALOPODA, 
the Squids and Cuttle-fish at p. r10; but the “pen,” 
or internal skeleton of /olgo vulgaris, the common 
Cuttle-fish, as well as the hard internal shell of Sefza 
officinalis, with specimens of the parrot-shaped_ beak, 
