8 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 Loven, 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 

 aiFords more than half the number of species found on the shores 

 of Great Britain and Ireland. The species most characteristic of 

 our locality are, — 



BuUsea pectinata,, Natica Montagui, 

 quadrata, helicoides. 



Bulla Cranchii, Groenlandica, 



Amphisphyra hyalina, Margarita helicina, 



Fusus Norvegicus, Nucula tenuis, 



Turtoni, Modiola nigra, 



Islandicus, Astarte compressa, 



Barvicensis, Necera cuspidata, 



Velutina plicatilis, Panopsea Norvegica. 

 Scalaria Trevelyana, 



* We limit our comparisons here to the marine MoUusca, as the geographi- 

 cal distribution of t?ie land and fresh water species has been treated of else 

 where. — See Newc. Nat. Hist. Trans. — Forbes in Brit. Assoc. Report, 1839, — 

 and Gray's Turton's Manual. 



