446 Bibliographical Notice. 



species of the genus ; and it appears to us that Mr. Jeffreys yields 

 everything when he acknowledges " it would seem as if a valid dis- 

 tinction existed in the length from the beak to the front margin 

 being always greater in P. ineequivalvis, and on the posterior side in 

 P. obtma ;" for the point of difference here alluded to will be found 

 to be constant and all-important. In P. obtusa, the greatest dia- 

 meter from the dorsal to the ventral margin is always situated 

 towards the posterior extremity of the shell, whereas in P. inaequi- 

 valvis it is anterior, or in a line drawn from the beaks. We have 

 examined more than 600 specimens of P. incequivalvis from Jersey, 

 for the express purpose of finding intermediate gradations between 

 that species and P. obtusa, but without meeting with any such 

 specimens ; and the more experience we have had of the two shells, 

 the more firmly have we become convinced that differing, as they 

 do, 1st, invariably in form, 2ndly, invariably in habits, and, 3rdly, in 

 geographical distribution, Pandora incequivalvis and P. obtusa can- 

 not but be regarded as vaHd and distinct species. 



By far the most interesting portion of the present volume is the 

 graphic and full account of the ship-worm (Teredo), to the history 

 of which the author devotes no less than forty-five pages. The details 

 respecting this genus have evidently been drawn up with especial 

 care, and must be read in their entirety to be appreciated. To 

 attempt to give here partial extracts would be doing the author an 

 injustice. Mr. Jeffreys describes only six species of the genus, 

 whereas, in his " List of the British Species of Teredo," published in 

 the 'Annals' of August 1860, no less than fifteen were admitted. 

 On examining the reasons for this wide discrepancy, we find that 

 Teredo nana, and T. subericola are now regarded as varieties of 

 T. megotara, and that T. bipinnata of Turton is the same as T. 

 pennatifera of Blainville — the former author having assigned in his 

 description the valves of one species (T. malleolus) to the pallets of 

 another (T. pennatifera). Again, T. bipartita, T.fusticulus, T. 

 spatha, and T.fimbriata {T. pahnulata, F. and H.) undoubtedly 

 have no claim to be admitted into our fauna. The valves and 

 pallets of these species have indeed been found in pieces of wood 

 floating in our seas ; but those woods have always been of extra- 

 European origin — West-India cedar and mahogany — and the con- 

 tained Teredines have never been met with alive, the animals 

 having apparently perished in the cold waters of our seas. 



We are, however, at a loss to understand upon what principle T. 

 malleolus and T. bipinnata {T. pennatifera, Blainville) are admitted, 

 while T. excavata and T. cucullata are excluded. These four species 

 occur under precisely similar circumstances, and are frequently found 

 associated together and living in the same pieces of European woods 

 drifted to our shores. We cannot acquiesce in the statement that 

 *' the habits of the Teredo are httoral," and that " when they are 

 met with far from land, the piece of wood which contains them has 

 been accidentally detached and carried out to sea by some marine 

 current." On the contrary, the four species just mentioned, though 

 frequently met with in floating balks of timber, have never as yet, 

 we believe, been found in fixed woodwork. They appear, like the 



