Salmo'iiidae 



17 



Lough Erne Pollan [G. pollan altior) and the Shannon Pollan 

 ((7. pollan elegans) (fig. 9) differ slightly from the typical form 

 found in Lough Neagh. Pollan are usually 8 to 12 inches long, 



Fig. 9. — Shannon Pollan. 



but sometimes measure 18 inches. An arctic marine species 

 that ascends the rivers of Siberia is the nearest relative of this 

 exclusively Irish fish. 



30. Powan, Coregonus clupeoides (fig. 10b).— The Powan of 

 Lochs Lomond and Esk, the Schelly (C chqyeoides stigmaticus) of 

 Ullswater and Haweswater, and the Gwyniad (C clupeoides pen- 

 nantii) of Bala Lake, are all forms of a species that is represented 

 in Scandinavia and Central Europe by a number of very similar 

 species or sub-species, including the Blaufelchen (C ivartmanni) 



A. B. 



Fig. 10. — Heads op (A) Houting and (B) Schelly. 



of the Lake of Constance. Coregonus muksun, a migratory arctic 

 species, is also closely related. The Powan is of the same size as 

 the Pollan. 



Houting, Coregonus oxyrhynchus (fig. 10a). — This is a migra- 

 tory species of the coast of Europe from Scandinavia to Holland ; 



c 



