APPENDIX. 247 



open anteally and posteally. The specimen examined measured 

 eight inches from the front valves to the terminal pallets, and 

 when the siphons are extended, an inch longer. The anterior 

 part of the animal is enclosed in a pair of hemispherical shining 

 white valves, with a large angular gape in front, and rounded 

 behind into auricles, which, in this species, are much larger than 

 in its congeners ; the body and mantle are fixed to them, and 

 proceed under the protection of a testaceous tube to the terminal 

 pallets, which are also encased within the tube. 



The branchise are invisible until the mantle is opened. There 

 is what appears to be a purple dull red labium on each side the 

 mouth, connected by a thin membrane ; these have been termed 

 salivary glands, and may perhaps be such. The oral aperture is 

 subtriangular ; the foot in the living animal appears bluish 

 hyaline, but when the moisture is absorbed it is muscular and 

 coriaceous, attached to the body by a thick powerful cylindrical 

 pedicle, and in its centre the terminus of the hyaline stylet is 

 visible ; the form of its basal area is that of the anterior gape, 

 which is of a diamond figure, with its angles placed vertically 

 and transversely, but the transverse axes are longer than the 

 vertical. A pair of yellowish-white spatulate appendages are 

 fixed to the posterior extremity of the body. In this animal, 

 besides the anterior and posterior apertures of the shell, there is 

 a rather extensive oval orifice on the dorsal surface of the shell, 

 which is covered by a thick subcircular rough skin, springing 

 from the internal part of the anterior end of the mantle, which 

 appears to have valvular function of closing the orifice." Clark, 

 in " Annals of Natural History," vol. vi. (1 850). 



Mr. Hanley has lately obtained a tolerable harvest of this 

 hitherto rare species from a submerged plank that had formed 

 part of the cargo of a timber-ship, wrecked off Guernsey some 

 years ago. The excavations made by these specimens (whose 

 stomachs were distended with sawdust) were not lined with cal- 

 careous matter, excepting at the exposed or caudal extremity of 

 the more adult ones, where the incipient tube was slightly con- 

 camerated as in Norvagica. Possibly, then, the large uncham- 

 bered tubes referred to in the body of our work, although brought 

 to Mr. Hanley by the carpenter he employed, along with the 

 valves, did not belong to them, or possibly the extreme ends had 



