THE society's NOTE-BOOKS. 201 



Gosse, in hi.s Natural History of Reptiles, speaks of the Ghecko 

 lizard, and on p. 86 describes the structure of the under side of 

 the toes as enabling them to cling to inverted surfaces as House 

 flies do. He says : — " The mode in which this is effected we do 

 not thoroughly understand ; but we may conjecture that it is by 

 the raising of these imbricated plates by muscular action, so as to 

 form a vacuum beneath the sole, when the pressure of the external 

 air causes the toe to adhere firmly to the surface." Gosse uses 

 the leather sucker a few lines further on as an illustration. The 

 Ghecko can, when alarmed, move very fast. * 



I do not profess to see hooks on the hairs of all fly's pads ; 

 they are not so easily to be seen on the Blow-fl3''s foot. I consider 

 the foot of the Breeze-fly as one of the best examples of "hooked 

 hairs " on the pads. I believe the Drone-fly and the Dung-fly 

 have straight hairs. The Ophion-fly has no hairs at all, I think. 

 The pad appears quite bare of them, and I think the pad of the 

 Wasp's foot is without hairs, and if so they cannot adhere by 

 means of a fluid poured out of expansions at the end of hairs. 



W. LOCOCK. 



I have carefully examined this slide with i/i2th o.g., and 

 cannot satisfy myself as to there being a single hooked hair. The 

 appearance is, in my opinion, due to the bulbous or blunted end 

 of the hair from which the viscid fluid is exuded, and the action 

 of reflected light in the lumen of the hair gives a hooked resem- 

 blance when the object is out of focus. I have observed the same 

 hooked appearance in some vegetable hairs, which poured out an 

 adhesive or sticky substance. R. S. Hudson. 



I cannot imagine what use hooked hairs would be if they 

 exist to a fly in walking upon glass, as we cannot detect any 

 irregularities on ordinary glass slips, even with high povi^ers. To 

 be of any use these hooked hairs must catch in some irregularities, 

 and not only catch, but must also hook around the irregularity to 

 be of any service. Compare the relative proportions of the foot- 

 pad hooks and the glass to an ordinary black beetle and a sheet of 

 paper. Although the beetle can climb up a white-washed wall, a 

 papered or painted wall puzzles him, and in the cockroach the 

 hooked claws are assisted by spurs on the elbows. From the 



