OF NORTHUMBERLAND AND DURHAM. 9 



Fusus antiqims and gracilis, Cyprina Islandica, and Modiola 

 vulgaris, from their size and frequent occurrence, form a conspi- 

 cuous part of our Fauna, but their general diffusion through 

 most of the British seas prevents our considering them as charac- 

 teristic of this locality. These species, however, are rare on the 

 southern coast of England. Of northern forms, whose absence 

 is deserving of remark, perhaps the most conspicuous is Lottia 

 testudinalis, so widely spread in northern latitudes and abundant 

 on many parts of the west of Scotland, as well as in Ireland and 

 Wales. T-his species does not appear to inhabit any part of the 

 eastern coast of Britain. Other northern species, not uncommon 

 on the western shores of Scotland, are also absent here ; of these 

 we may mention Lima hyans, Terehratida caput-seriJentis, Cra- 

 nia anomala, Pecten niveus, and nebulosus, Leda pygmcea and 

 Margarita carnea. The following south of England species do 

 not occur with us, — 



Bulla hydatis, Ovula patula, 



Eulima polita, Fissurella reticulata, 



Scalaria clathratula, Calyptrasa Chinensis, 



Truncatella Montagui, Modiola Gibbsii, 



lanthina fragilis. Area lactea, 



Rissoa crenulata, Cardium aculeatum, 



striatula, exiguum. 



Phasianella pullus, Cytherea chione, 



Trochus umbilicatus, Tellina depressa, 



striatus, Petricola irus, 



crassus, Pandora obtusa, 



Pleurotoma gracilis, Galeomma Turtoni, 



septangularis, Gastrochasna pholadia, 



purpurea, Pholas parva, 

 Fusus muricatus, papyracea, 



Erato Isevis, dactylus. 



These may all be considered southern forms which have not 

 reached our limits, but it is worthy of remark that some of them 

 attain a much higher latitude on the western side of Great Bri- 

 tain than they do on the eastern. Many others might be added, 



