78 BEACH GRASS 



of his six feet, the groove made by his body and 

 the deep marks in the sand made by his powerful 

 hind feet as he hops away are all characteristic. 



The tracks of caterpillars on the sand are cu- 

 rious and at times very striking features. They 

 are seen to best advantage when the surface of 

 the sand is pit-marked by rain, for the passage of 

 the caterpillar's body smoothes or planes the 

 surface and the track shows well by contrast. 

 A large woolly-bear caterpillar that I encountered 

 in the dunes one August day was making a 

 straight course with considerable speed over the 

 dry but rain-marked . sand. Its track was half 

 an inch wide and perfectly smooth, for his rough 

 hairs brushed off the irregularities in the sand 

 he traversed. At times a narrow central ridge 

 showed, made by the interval between his pairs 

 of false legs. Where he struggled up an incline, 

 cross lines appeared made by the digging in of his 

 vigorous true legs in front. When I attempted 

 to examine him and put him through his paces 

 on the sand, he curled up in a ball and played 

 possum. 



It is evident that woolly-bear caterpillars de- 



