(COLOGY OF CIRRATULUS TENTACULATUS. 69 
In view of such a method of feeding, the idea of a food-catching function 
on the part of the filaments must be rejected. Moreover, as the mouth of 
the worm in its burrow is situated some distance beneath the surface and 
the filaments are waving in the water above, bow is any such function 
practicable ? 
I am convinced that it is only under direst necessity that Cirratulus 
quits its burrow, and then it is certainly not to swim about actively, as 
M. Bounhiol suggests, but merely to crawl sluggishly on the surface of the 
Fic. 7.—Diagrammatic median longitudinal section through the anterior end 
of Cirratulus. 
mud. If by an accession of clean water the symptoms of asphyxia are 
removed, the worm will immediately recommence burrowing. 
Nor are the filaments used to collect sand particles. Sand particles 
adhere to the mucus exuded by the body of the worm, and by so doing 
probably prevent the walls of the burrow from caving in. They thus 
allow the animal greater freedom of movement, but there is certainly 
nothing that can be dignified by the name of a tube. 
In conclusion, I wish to thank Mr. F. 8. Wright for his able execution 
of the drawings for half-tone blocks for this paper. 
