1847.] On Teredo Navahs, $c. 489 



[The valuable hint contained in Dr. Cantor's communication will 

 doubtless be appreciated by all such as are interested in the protection 

 of wood-work from the attacks of the Teredo. Nowhere would this 

 natural opponent of its ravages be more serviceable than in the Hugh; 

 but the Mytilacea are, strictly speaking, inhabitants of salt water, 

 although some of the family are capable of being localised in rivers, 

 as is the case with Dreissina polymorphus, discovered by Pallas in 

 the Volga, and some species of Modiola. The valves of two species 

 of Mytilus have occasionally brought to me from the Hugh ; one, 

 closely allied to M. edidis, but less ventricose, and easily distin- 

 guished from it by the cardinal teeth ; the other apparently identical 

 with the M. crenatus of Lamarck, figured in the Conchologia Systema- 

 tica of Reeves ; but as neither of these, nor Dreissina, of which I have 

 several specimens, have been found alive, I think their presence 

 altogether accidental ; they may have found their way to this river 

 either with ballast or adhering to the bottoms of vessels. Modiola 

 e.marginata, (Benson,) however, inhabits the water of Tolly's nullah, as 

 I was informed a few weeks ago by its distinguished describer himself. 

 —J. W. I,] 



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