226 YEAR-BOOK OF FACTS. 



trance or mouth of the tube, and thus prevent the intrusion of 

 crustacean and annelidan foes. The length of the tube is of course 

 equal to that of the animal, which is attached to it by strong muscles 

 in the palletal-ring, and varies in the different species from three 

 inches, or even less, to as many feet. The internal entrance or 

 throat of the tube is also distinguishable in each species by its pecu- 

 liar transverse laminae, and frequently a longitudinal siphonal ridge. 

 Monstrosities not unfrequently occur in the valves and pallets ; and 

 in one instance the pallet-stock is double, showing a partial redun- 

 dancy of organs, as exemplified by the author with respect to the 

 operculum of the common whelk. More than one species often in- 

 habit the same piece of wood ; and want of sufficient care by natu- 

 ralists in extracting the valves with their proper tubes and pallets 

 may account in a great measure for the confusion which exists in 

 public and private collections, and which has thence found its way 

 into systematic works. 



The Teredines have many natural enemies, both in life and after 

 death. In the south of Italy, and on the North African coast, they 

 are esteemed as human food. In Great Britain and Ireland, four 

 species occur in fixed wood, and eleven others in drift wood, the 

 latter being occasional visitants. Of these, no less than six have 

 never yet been described, and two others are now, for the first time, 

 noticed as British. The number of recorded exotic species only 

 amounts to six more, making a total of twenty-one ; but it is pro- 

 bable that when the subject has been more investigated, a considerable 

 addition will be made to this number. Mr. Jeffreys then expj 

 the distribution of the littoral species on the shores of Great Britain 

 and Ireland, and produced a -synoptical list with descriptions of the 

 new species. He believed all the Teredines were marine, except 

 possibly Adanson's Senegal species, and one which had lately been 

 found in the River Ganges, the water of which is fresh for about 

 - ii hours out of the twenty-four, and brackish during the rest 

 of the day ; but as a well -known exception of the same kind occurs 

 ennsof marine shells (Area), and t..e transition from fresh to 

 brackish, and thence to Bait water, is very gradual, such exceptions 

 should not be regarded with suspicion or surprise. He concluded 



this pari of the Subject by exhibiting some drawings and specimens, 



and acknowledging bis obligations to Dr. Lnkis and other bcA 

 friends. He next treated the subject in an economical poinl of view, 

 and remarked that, although the rrenob Government had issued two 

 commission! at different times, and the Dutch Government had 

 lately published the report of another commission, which wan ap- 

 d to inquire inte the mode of prevent!] or the 



:d harbours of those countries, om- own Go- 

 vernment bad "lone nothing. He alluded to the on 

 various remedies which had bean proposed during the last two or 

 three centuries, from time to time, son;.- of which wt re n rj absurd ; 

 hut he considered, from a study i tare's habits, that the 



most effectual preventive would l- impo ition, 



like that which has been proposed by Professor Ansted for coating 



