102 CATALOGUE OF THE MOLLUSCA 
‘boats, together with the great uncertainty of the weather when 
the grounds are reached, are drawbacks which will prevent its 
being often attempted. A trial made by Mr. Howse of dredging 
in fifteen to twenty fathoms water, undertaken for the purpose of 
gaining information for this Catalogue, has been attended with 
better success, as the notices of species obtained by it will 
shew. 
The Molluscan Fauna of the coast of Northumberland and Dur- 
ham partakes, as might be expected, much more of the characters 
of that of northern Europe than of more southern latitudes. On 
comparing it with the “Index Molluscorum” of Lovén, we find 
that about half the species of our Catalogue are inhabitants of the 
Scandinavian shores, whilst scarcely a fifth part are to be found 
in the Mediterranean. In both cases the greater proportion are 
bivalves. Dr. Philippi enumerates about one hundred and fifty* 
marine species, common to Britain and Sicily, but not more than 
a third of them reach our north-eastern shores, and it is curious 
that none of the latter are really southern forms, they being near- 
ly all of a cosmopolite character and equally common to the 
north of Europe. Compared with the British Fauna our coast 
affords more than half the number of species found on the shores 
of Great Britain and Ireland. The species most characteristic of 
our locality are,— 
Bullea pectinata,, Natica Montagui, 
quadrata, helicoides, 
Bulla Cranchii, Groenlandica, 
Amphisphyra hyalina, Margarita helicina, 
Fusus Norvegicus, Nucula tenuis, 
Turtoni, Modiola nigra, 
Islandicus, Astarte compressa, 
Barvicensis, Nera cuspidata, 
Velutina plicatilis, Panopzea Norvegica. 
Scalaria Trevelyana, 
* We limit our comparisons here to the marine Mollusca, as the geographi- 
cal distribution of the land and fresh water species has been treated of else 
where.—Sce Newc. Nat. Hist. Trans.—Forbes in Brit. Assoc. Report, 1839,— 
and Gray’s Turton’s Manual. 
