26 



times only a depression. To it a nerve is given which expands on 

 the apex of the cavity. 



The author then describes groups of organs, allied in form to those 

 on the palpi, which are to be found on the legs of all insects yet 

 examined. There are about three groups situated about the tro- 

 chantero-femoral joint, and to them nerves can be distinctly seen 

 proceeding ; and in Meloe the branch is seen to pass up the opening in 

 the wall, to terminate in a papilla in the centre of the membrane 

 covering it in. 



It is also shown that the bladder-like apex of the palpi, instead 

 of being smooth, as is generally described, is covered with a great 

 number of small bodies, something in form like ninepins, some- 

 times exceedingly small, requiring a J-inch objective to make them 

 out, when they can clearly be discerned to be a modified condition of 

 true hairs, copiously supplied with nerves. The author names these 

 " tactile hairs," and points out their existence in all palpi used for 

 touching, and in other organs subservient to that function. These 

 tactile hairs are very large in the palpi and antennae of Dyticus mar- 

 ginalis. The barrel-like organs of the Lepidoptera are next investi- 

 gated, and are shown to have a nerve passing up them ; but whether 

 proceeding to the apex of the nipple-like papilla on them or not, 

 cannot be quite made out. They are pointed out as being nearly 

 allied to the organs on each of the palpi of the Earwig (Forficula 

 auricularia) . 



The author refers to the sacs found on the antennae of all insects, 

 which have been fully treated of in two papers read by him before the 

 Linnean Society, and published in their ' Transactions ;' and he lastly 

 examines the probable functions of all these organs, which must be 

 of sensation, probably special. 



Attention is also called to the value of bleaching the tissues by 

 chlorine in investigating the structure of insects, which process was 

 first used by the author and described by him in the papers above 

 mentioned. 



About forty drawings accompany the paper illustrative of the 

 structures described. 



