256 ADDENDA. 



of an oblong shape, and detached on their internal edge, as in the 

 Teredo bipennata ; in having the striae on the triangular processes 

 in front remote and not half as many in number ; and in the shape 

 of the accessorial valves, which are transverse 'and not unlike a 

 mallet, as is represented something magnified in our plate, and 

 whence its specific name. From Teredo Bipennata it differs in the 

 accessorial valves : and from the Teredo Nana in the distinct auricles 

 underneath, a character not found in this last species ; and in the 

 want of the strong conic tooth on the cardinal margin. 



In some late heavy gales, a piece of spar, supj)osed to have 

 formed part of the Venerable man of war, wrecked in Torbay 

 about fifteen years since, was drifted into the bason of Torquay, 

 covered with the Lepas anatifera, and filled with this very distinct 

 species of Teredo. The tube consists of a slight testaceous deposit 

 on the surface of the chamber, the termination of which is slightly 

 semiconcamerated : the accessorial valves are terminal, and appear 

 through a minute and rather elongated perforation on the outer sur- 

 face of the wood. 



Besides the Xylophaga Dorsalis above described, we have before 

 us four distinct and well defined species of Teredo. Two of these 

 are furnished with an ear-shaped process on the inside of the 

 valves, at the outer angle under the hinge, having the inner margin 

 detached and forming a straight transverse edge, and the outer mar- 

 gin much reflected : these are the T. bipennata, and the T. Malleolus ; 

 the former of which has the accessorial appendages very long, 

 linear, and feathered ; the latter has the accessorial appendages 

 transverse and mallet-shaped, with a slender point rising like a 

 handle from the middle, as is represented in our plate 2, fig. 19. 



