THE PHILOSOPHY OF XESURUS 295 



individuals propping themselves for a moment on 

 this part of the body, the ventral spines acting as 

 two legs of a tripod, or again pushing hard against 

 the rock when the fish slid over a sharp angle. 



Whether from disuse or lack of incentive, these 

 fish seldom exhibit any burst of speed, although 

 the dorsal and anal fins were long and deep and the 

 tail and the pectorals large and powerful. When 

 moving along or feeding, I never saw an unusually 

 swift movement, and even when I was harpoon- 

 ing them, and now and then thoroughly alarming 

 them, they never showed more than an ability to 

 avoid an awkward thrust of the grains. I could 

 easily spear a half dozen of them to any one of an- 

 other species, and not because of their abundance. 



Another argument in favor of the lack of ene- 

 mies was the very considerable variation existing 

 among Xesurus. In a large school I saw some 

 which were exceedingly deep in the body, and 

 others a full third lower; the lateral line might 

 be present or absent, and comparison of pectoral 

 fins of different fish showed very marked varia- 

 tions in size and outline. Fish which live very 

 strenuous lives, whose numbers are kept down to 

 low limits and which are beset by numerous ene- 

 mies, exhibit little variation from the normal, — 

 they keep to the narrow, sharp line of sheer ex- 

 istence and every character tells — any latitude in 

 one or another direction might well wipe out the 

 whole race. 



Again and again they came to the crab meat, 

 but I never saw them nibble at it. The attraction 



