214 PHOLADID A. 
living specimens of this rare species, unmixed with any other, 
many of which were apparently full-grown and 10 inches in 
length; some I examined alive and dissected fresh, and many 
others from spirits. These facilities have, I thik, almost 
put it in my power to give a tolerably general idea of the 
animal, though it may not be a complete anatomical detail. 
Under the circumstances I have stated, I am inclined to think 
that the following notes may afford malacologists some infor- 
mation, and enable them to compare my humble attempt with 
the anatomies of Teredo by the great masters in this branch 
of science. Agreeably to my usual method I commence with 
the external description of the animal, and then proceed to its 
anatomy. 
T. Mecorara, Hanley. 
T. megotara, Brit. Moll. i. p. 77, pl. 1. f. 6, & pl. 18. f. 1, 2. 
Animal vermicular, pale bluish-white, inclosed in a sub- 
cylindrical elongated tubular mantle, not of very thin texture, 
only open anteally and posteally. The specimen examined 
measured 8 inches from the front valves to the terminal 
pallets, and when the siphons were extended, an inch longer. 
The anterior part of the animal is inclosed in a pair of hemi- 
spherical shining white valves, with a large angular gape in 
front, and rounded behind into auricles, which in this species 
are much larger than im its congeners; the body and mantle 
are fixed to them, and proceed under the protection of a tes- 
taceous tube to the terminal pallets, which are also encased 
within the tube. 
It will here be convenient to observe, that the calcareous 
tube through which the body passes, to be spoken of more in 
detail hereafter, has hitherto been considered as one of mere 
protection ; but I shall show that though the globular valves m 
front work free in the tube, it is as much a part of the animal 
as the shell of the Pholades, masmuch as it is fixed to it pos- 
teriorly by a very strong muscle. 
The branchize are imvisible until the mantle is opened. 
There is what appears to be a purple dull red labium on each 
side of the mouth, connected by a thin membrane ; these have 
