26o ENTOMOLOGICAL NEWS. [November, 



footing than the cork that they could pull approximately one- 

 sixth more upon the former than upon the latter. The aver- 

 age pull in experiment i was 17.725 grams (17.07:1) ; while 

 that in experiment 2 averaged 20.417 grams (19.66:1). 



But it was in experiment 3, when pulling under the condi- 

 tions most closely approaching those in which they are usually 

 found, that these beetles performed their most astonishing feats 

 of strength. Their average pull in this case was 164.83 grams 

 (158.73:1); while the maximum pull was 232. grams (211.0:1). 

 Experiment 4 was made to find the strength of the tarsi and 

 the ability of the beetles to climb with a weight (Fig. 4). The 

 individuals showed considerable variation in this respect, some 

 being able to climb with twice the weight that would pull 

 another down. The tarsi are slender, comparatively weak and 

 evidently not adapted to such work ; still the beetles showed 

 themselves able to climb with an additional burden of ten times 

 their weight. 



It was noticed that the insects could crawl from under what 

 seemed to be an almost crushed weight, so experiment 5 was 

 performed to determine their power to lift weights upon their 

 backs. The thread fastened around the pro-mesothoracic con- 

 striction as before was passed down through a slit cut in a 

 piece of cork, upon which the beetle stood and attached either 

 to the platform to receive the weights or to the spring previ- 

 ously described. Although laboring under the decided disad- 

 vantage of having the weight suspended from the most slender 

 part of their bodies, they still cleared their abdomens from the 

 cork while lifting a weight of 104.67 grams (100.781:1). 



In a single trial one specimen succeeded in crawling along a 

 sheet of cork with a weight of 700 grams placed upon a small 

 platform upon its back ; but 750 grams held it still. These 

 weights seem sufficiently enormous to crush the little creature, 

 although the beetle used showed no ill effects from the great 

 pressure. The ability of these insects to support such weights 

 is undoubtedly due to the unusual hardness of their exoskele- 

 ton : a character in which there exists wide variation, how- 

 ever, within the limits of this species. 

 The last experiments — 6 and 7 — were suggested by the ten- 



