86 Dr. J. E. Gray on the Structure and Position of Teredina. 



arriere en un tube complet h orifice terminal unique V (Man. 

 Malacol. p. 579, 1825.) 



The existence of the dorsal buckler or plate at once shows 

 the affinity of these fossils to Pholas. 



James Sowerby the elder figured the shell in his ' Mineral 

 Conchology/ and referred it to the genus Teredo, under the 

 name of Teredo antenautica, overlooking the character afforded 

 by the dorsal plate, which is always absent in Teredo, and the 

 absence of palettes, or terminal opercular valves, as they have 

 been called, and a containing shelly tube, which are always pre- 

 sent in that genus. 



M. Deshayes, in his f Coquilles fossiles de Paris/ retains the 

 two families, les Tubicoles and les Pholadaires; of Lamarck, and 

 gives nearly the same character for the genus as that quoted 

 from De Blainville's work ; only he calls the cuilleron of De Blain- 

 ville palettes ; but this is evidently a slip of the pen, as the part 

 described is always called a cuilleron by French authors, in the 

 genera Pholas and Teredo, which alone, with Teredina, possess 

 the process under the umbo so referred to. He adds, — " Ce 

 genre fait evidemment le passage aux Taret" (Teredo) (vol. i. 

 p. 18). 



Deshayes, more lately, in his notes to the new edition of 

 Lamarck, observes, " Le genre eurieux des Teredines n'a pas ete' 

 bien connu de Lamarck; sans cela il lui aurait donne des ca- 

 racteres plus complets. La Teredine est une veritable Pholade 

 globuleuse fixee h l'extremite d'un tube" (vol. vi. p. 34). 



Mr. Woodward, in his ' Manual/ which is specially devoted 

 to the determination of fossil shells, overlooking these observa- 

 tions, and perhaps misled by the position of the shell in the old 

 work of James Sowerby the elder, regards Teredina as a sub- 

 genus of Teredo ! He further observes, " Valves with an acces- 

 sory plate in front of the umbo, free when young, united by the 

 margins of the shelly tube when adult (?). The tube is some- 

 times concamerated, its siphonal end is often truncated, and the 

 opening contracted by a lining, which makes it hour-glass shaped 

 or six-lobed (fig. 25 a)." {' Manual/ p. 330.) 



The fossil Teredina has been considered as a Teredo by 

 James Sowerby, a Fistulana by Lamarck, as a subgenus of 

 Teredo by Woodward, and as a genus intermediate between Teredo 

 and Pholas by Deshayes, but who still arranges it in a distinct 

 family from the latter; and latterly, M. Deshayes has considered 

 it as a species of the genus Pholas; and in my genera of the 

 family Pholadida I placed it as a genus of that family. 



A careful examination of the structure of the shell and its 

 tube, as it has been called, show that it is, as M. Deshayes ob- 

 serves, a true Pholas. Indeed, it ought to have been referred 



