256 ADiyENDA. 



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

 the Teredo bipennata ; in having the striae on the triangular pro- 

 cesses 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 tho 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, supposed to have 

 formed a 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 ap- 

 pear through a minute and rather elongated perforation on the 

 outer surface 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 margin 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 



