INTRODUCTIOX. CXV 



and a still smaller number in a south-easterly direction 

 (Hastings). These give a peculiar interest and charm to 

 the marine fauna of Devon and Cornwall and the Channel 

 Islands. Amongst them may be named Mimosella gracilis, 

 Lichenopora radiata, Diastopora Sarniensis, Entalophora 

 clavata, Retepora Couchii, Lepralia adpressa, Lepralia 

 foliacea*, Schizotheca fissa, Smittia cheilostoma, ScMzo- 

 porella Cecilii, S. sanguinea, S. vulgaris, S. armata, S. 

 venasta, Dipornla verrucosa, Cribrilina GattycB, C. figularis, 

 Microporella violacea, Cabtrea Boryi. 



Other southern forms extend much further north ; and 

 a small group occurs in the Shetland seas. A very limited 

 number have found their way to the north-east of Scot- 

 land and England ; and in similar cases Mr. Norman has 

 shown it to be probable that migration has taken place along 

 the western and northern and down the eastern coasts f- 



The north-eastern district is characterized by the pre- 

 valence of Arctic and boreal forms^ and the absence for the 

 most part of distinctively southern species, even of such 

 as have found their way as far north as Shetland. 



Amongst the British Polvzoa we find a number of 

 erratic species having a wide and somewhat anomalous 

 range. For instance, Cellaria fistulosa has occurred in 

 the Mediterranean and at Madeira, in South Africa, in 

 Scandinavia and North America, in the Indian Ocean, 

 in Australia and New Zealand. Microporella ciliata, 

 another cosmopolitan form, ranges to Florida, California, 

 the Arctic seas, Scandinavia, South Africa, the Arabian 

 sea, Australia, and New Zealand. M. Malusii has been 

 found in the Arctic seas, Scandinavia, the Black Sea, the 



* L. foUacea has occurred in the Hebrides. 



t Bugula turhinata is probably a southern form which has thus made its 

 way to the Duvliam and Yorksliire coasts. 



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