608 The American Naturalist. [July 
ZOOLOGY. 
The Antennal Sense Organs of Insects.'—During his studies 
carried on in Leuckart's laboratory on the peculiar sense organ in the 
the base of the antenna of certain Diptera (Mochlonyz culiciformis, 
Corethra plumicornis), Mr. C. M. Child found that the organ occurs 
generally in Diptera, and, if not generally, at least very often in the 
other orders of Insects. 
In the wasp ( Vespa vulgaris) the organ occurs in the second joint of 
antenna. Near the end of the first joint the main nerve of the antenna 
gives off branches on all sides. "These run toward the periphery of the 
second joint, connecting with ganglion cells, which in turn connect with 
small rod-like bodies that end in the articular membrane between the 
second and third joints. "These rods are gathered into groups each of 
which ends in a pore in the membrane. On the outside of the antenna 
no sense hairs are found corresponding to these pores, which seem to be 
closed on the outside. Between the rods nuclear elements were found, 
but whether they were of connective tissue or of nerve elements was 
not determined. An organ similarly placed and of similar structure is 
to be found in the genera: Melolontha (Coleoptera), Epinephele (Lep- 
idoptera), Bombus (Hymenoptera), Pachyrhina, Tabanus, Syrphus, 
Helophilus, Musca, Sarcophaga (Diptera) Sialis, Panorpa, and Phryga- | 
nea (Neuroptera), Libellula (Pseudoneuroptera.) 
Of the Hemiptera only the Homoptera were investigated. Here the 
rods and ganglion cells are fewer in number. Periplaneta, Locusta 
and Stenobothrus among Orthopteran genera have a structure in the 
second antennal joint with ganglion cells and long fibrous rods. 
Thysanura were not studied. 
In certain Diptera (Culicids and Chironomide) the organ is somewhat. 
different. At the base of the antenna of both sexes there is a nearly 
spherical joint. This is larger in the male than in thefemale. In the 
latter the nervous structure within this joint is much more readily com- 
parable to the organ described for the wasp than that inthe male. But 
even in the male the structure may be reduced to the general type. In 
the female the rods instead of ending at the periphery of the second 
joint are directed toward the middle of the long feeler. The large 
antennal nerve runs chiefly to the ganglion cells, giving off two small 
branches that run on into the other joints of the antenna. There is no 
! Zool. Anz. XVII, p. 35, 1894. 
