348 TOILERS IN THE SEA. 



one character, and consisted of an aperture bored 

 through and through, but having the entire thick- 

 ness of the shell wall, from the inner surface to the 

 outer one, as it were countersunk. Accordingly, in 

 section, such a perforation would present a trun- 

 cated cone, the apex of which is directed inwards." 1 

 These observations seem to indicate that double- 

 capacity, exhibited by many annelids, of boring 

 chambers for themselves in hard substances, and 

 then lining them with a tube, or of constructing 

 independent tubes, and thus being either excavators, 

 or tube masons, according to circumstances. 



There is a brown or dusky worm, about an inch 

 in length (Dodecaceria concharum}, which bores its 

 chambers in one of the hardest of our marine shells. 

 It has no eyes and no proper head, but there are a 

 pair of long tentacles on the terminal joint, which 

 occupies the place of a head, and beneath these three 

 or four pairs of slender filaments. " When at rest 

 under water the worm protrudes the tentacles and 

 filaments from the circular opening of its burrow. 

 The filaments are laid along the shell, and kept quiet, 

 or moved about like independent worms." Johnston 

 never saw them capture any prey. " The excrements 

 are pushed out at the same aperture, and may be 



1 " On the Boring Powers of Minute Annelids," by G. C. 

 Wallich, in "Annals Nat. Hist.," vol. ix. (1861), p. 57. 



