C. M. YONGE 



(quoted by Gardiner, 1931), the largest Indo-Pacific species "are 

 Leocrates (Eunice) siciliensis, Lijsidice coUaris and some of the 

 CirratuHdae. The former two have enlarged gouge-shaped lower 

 jaws, with hard, though calcareous, cutting edges, which are ob- 

 viously their boring tools, but the latter have soft bodies and no 

 conspicuous hard parts at all." Unlike that of the sipunculids, the 

 mode of feeding of related nonboring species does not indicate that 

 thev may get food bv boring. Like the temperate-water Polijdora 

 (described later), they may bore solely for protection. Study of 

 these forms in life would solve this problem. 



The turbellarian flatworm Pseudostylachus ostreophagus, which 

 is a native of Japanese waters but was introduced into Puget Sound 

 with consignments of Japanese oysters (Crassostrea gigas), attacks 

 the oysters when young, making a keyhole-shaped opening in the 

 shell and then eating the contained animal. The process of boring 

 is unknown, but in the absence of jaws or any other hard structure 

 must involve chemical means. Certain carnivorous Gastropoda, nota- 

 bly the prosobranch Muricidae and Naticidae, bore through the firm 

 calcareous shells of their prey, usually bivalves, by the mechanical 

 action of the radula assisted by acid secretion from an accessory 

 boring organ ( Carriker, 1961 ) . Later the flesh of the prey is rasped 

 out by means of the radula. Full description of the processes in- 

 volved is provided by Carriker and his co-workers in chapter 3 of 

 this symposium. 



Indirect association. We are here concerned with animals which 

 scrape the surface of calcareous rock to obtain the algae which grow 

 upon it or bore superficially into it. This is true of species of largely 

 intertidal prosobranch Gastropoda, of such genera as Nerita and 

 Turbo, which cut into the softened rock surface with the broad 

 radula and assist in the formation of the characteristic intertidal 

 "nick" along the landward margin of coral reefs ( Doty and Morrison, 

 1954; Newell, 1955, 1956; Newell and Imbrie, 1955)'. But in no real 

 sense can these gastropods be said to bore. 



Much the same habit exists in a variety of echinoid echinoderms 

 (sea urchins) which excavate new borings or enlarge old ones by 

 means of the teeth and spines. This is purely for protection, primarily 

 against wave action but to some extent on exposed shores against 



