Dr. J. B. Hicks on certain Sensory Organs in Insects. 229 



of the anatomical structure of the stems of Monocotyledons and 

 Dicotyledons, especially in reference to some objections taken against 

 the author's views respecting the stems of the Nymphaeaceoe. Cer- 

 tain peculiarities of the structure of roots are next examined ; and 

 these are shown to be formed on the Dicotyledonous type in 

 Victoria. 



The germination of the seed is described in a manner differing to 

 some extent from the accounts given by Planchon, Trecul, and 

 Hooker. The error of Trecul, in stating that the earlier leaves are 

 devoid of a stipule, is shown to depend upon his overlooking the 

 true axillary position of that organ. 



The Phyllotaxy is next treated, with the development and arrange- 

 ment of the leaves and roots ; lastly, a complete history of the develop- 

 ment of the flower, showing that the apparently inferior position of 

 the ovary depends upon a great enlargement of the receptacle after 

 the formation of the various organs forming the flower. 



May 26, 1859. — Sir Benjamin C. Brodie, Bart., President, in the 



Chair. 



" On certain Sensory Organs in Insects, hitherto undescribed." 

 By J. Braxton Hicks, M.D. Lond., F.L.S. &c. 



The author commences with an allusion to papers published in the 

 Linnean Society's 'Journal' and 'Transactions' respecting groups of 

 organs, abundantly supplied with nerves, on the bases of the halteres 

 of Diptera, also on the nervures of the wings and on the elytra of 

 Coleoptera, and now gives a drawing which shows forth these organs 

 and the nerve proceeding to them on the halteres. He then describes, 

 for the first time, somewhat similar organs on the apices of the palpi 

 of some Diptera, and on their base in many Hymenoptera, as Apis, 

 Vespa, Nomada, Megachile, Bombus, &c. These are well shown in 

 the Vespa Crabro, or Hornet, where the nerve is seen expanding in 

 the thin membrane which covers in the opening beneath in the wall of 

 the member. 



In the paper, also, it is pointed out for the first time, that on the 

 apex of the palpi of Lepidoptera there is invariably found a structure 

 which is more or less of a cavity, generally tubular, and sometimes 

 extending inwards nearly the length of the last segment, but some- 

 times only a depression. To if 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- 



