322 I N A G U A 



adorned rocks. Their strange dorsal spines, I noted, were 

 folded well out of the way, and were raised only occasionally. 

 These spines, which comprise the first dorsal fin, are con- 

 structed in a most ingenious manner. At their bases is a com- 

 plicated locking device, so cleverly arranged that when the 

 first spine is erected it cannot be lowered from without until 

 the third is depressed. When this is done the entire fin auto- 

 matically folds down with it. I watched them carefully for 

 a long time hoping to catch some hint of the reason for this 

 strange contrivance. It is considered as a protection against 

 enemies, though this theory does not account for the unlock- 

 ing action of the third spine. Unless this is first lowered, how- 

 ever, when pressure is applied the other spines will usually 

 break before they give. 



Between the triggerfish were swarming large numbers of 

 porkfish, handsome striped creatures, gleaming with iridescent 

 color. Like the triggers they were feeding off the algae, but 

 their method and food was quite different. The triggerfish 

 were scraping low lying mosses; the porkfish confined their 

 activities to the larger, more rounded heads of vegetation 

 where they seemed to search carefully, probing between the 

 fronds, snatching up the small crustaceans, worms and other 

 invertebrates that made the algae their homes. 



With a five-pointed spear that I took down with me I tried 

 to add one of these porkfish to my collection. I missed it com- 

 pletely but on a second try snared one through the top of the 

 back. Before I could grasp it to place it in the mesh bag I car- 

 ried tucked in my belt for the purpose it had twisted loose, 

 and squirming in pain it floated lopsidedly past the cliff wall. 

 Before it had drifted very far there was a rush of fins and it 

 was seized by a rock hind, a large mottled fish covered with 

 reddish spots which, unnoticed by me, had been lurking in a 

 wide crevice. The hind returned to its shelter carrying its vie- 



