318 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 
I am somewhat uncertain whether this shell properly belongs in the genus 
Xylophaga, but it may be immature, and the accessory lamin may be later in 
developing. At all events the form and sculpture of the shell are so much 
more nearly like that of Xylophaga, as figured by Chenu, than like any other 
Pholad, that I prefer to place it here awaiting other information. Some 
years ago what appeared to be exactly the same species was shown me burrow- 
ing in the hempen covering of part of the first Atlantic cable; said to have 
been recovered from the North Atlantic at a depth of over 1500 fms. The 
siphons were simple, and it showed no accessory plates. 
