318 BULLETIN OF THE MUSEUM OF COMPAKATIVE ZOOLOGY. 



I am somewhat uncertain whether this shell properly belongs in the genus 

 Xylophacja, but it may be immature, and the accessory lamina; 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. 



