262 ENTOMOLOGICAL NEWS. [November, 



less exact idea of the real strength exerted by the insect than 

 do the preceding figures. The average dimensions of the 

 sexes, obtained from measurements of four males and four 

 females that were used in the experiments, were as follows : 

 Length, males, 3. 115 cm.; females, 3.32 cm.; breadth, males, 

 1.065 cm.; females, 1.14 cm. 



The average weight of all the specimens used during all of 

 the experiments was found to be 1.0384 grams. 



The six beetles put through all of the experiments continu- 

 ously lost an average of 2.89 per cent, of their weight during 

 the time of the work ; while the two beetles used as checks 

 lost only .62 per cent, in the same time. Still no relation could 

 be seen between the percentage of weight lost and the amount 

 of work done. 



No secondary sexual characters were found which could be 

 relied upon to distinguish the sexes, but upon dissection of 

 eleven of the beetles used it was found that seven were males 

 and four were female. While the largest beetles were females 

 and the smallest were males, those of medium size might be of 

 either sex. 



When subjected to interference or restraint, the insects, both 

 males and females, produced a sharp, intermittent, hissing 

 stridulation. 



In closing, I wish to express my thanks to Professor C. H. 

 Fernald and Dr. H. T. Fernald for their encouragement and 

 assistance in the preparation of this paper. 



EXPLANATION OF PLATE X. 



1. Dorsal view of Passalus cornutus Fab., natural size. 



2. Apparatus used in experiment i. 



3. The artificial burrow used in experiment 3. 



4. Apparatus used in experiment 4. 



5. Apparatus used in experiment 6. 



"Em'nent foreign scientists have found out that a grasshopper's ears 

 are in its legs." 



" How did they ascertain that ? " 



"They put the 'hopper' on a board and tapped the board gently." 



"The creature hopped away. Then they cut off its legs, put it on a 

 board again, and tapped the board as before, and it didn't hop away. It 

 couldn't hear the tap, you see." 



" What a wonderful thing science is." — Chicago Tribune. 



