1901] MICROSCOPICAL JOURNAL 299 
Extracts from Postal Microscopical Society’s Note—books. 
Edited for Science Gossip. 
Eristalis Tenax, Longitudinal Section of Halter.—For 
convenience of examination the halter of the fly may be 
divided into three separate parts, viz. base, pedicle, and 
globe or head. On the exterior surface of the base there 
are three distinct areas or sets of sense organs which have 
severally an anterior, posterior, and lateral aspect. These 
have long beén considered special sense organs. The 
lower area is somewhat rounded on the face, and covered 
with delicate elevations of the epidermis which take the 
form of circular papillae. They are divided into rows, 
and between each row there is a line of curved hairs. 
Lowne states that there are two distinct sets of these 
lower organs, and Theobold in his work on the “British 
Flies” has repeated this statement; but in no instance 
have I met with more than one, and it has invariably a 
lateral aspect. The two upper organs are placed on op- 
posite sides of the halter, one anterior and the other pos- 
terior. They are much longer and larger than the lower 
one, but like it in having rows of ridges beset with pap- 
illae separated by fine hairs. Several sections show the 
lining epithelium remarkably well. In this place it is 
especially modified to form a sensory or nerve epithelium. — 
The pointed ends of the cells are seen penetrating the 
papillae of the lateral organ. The halters receive their 
rich supply of nerves direct from the second thoracic 
ganglia. This pair of nerves is the largest in the thorax, 
and crosses to the opposite side immediately on entering 
the ganglia. The pedicle is a hollow tube connecting 
the base of the halter with the globe. On the external 
surface it is covered with hairs. The interior is divided 
by a septum which is continued the whole length. A 
large tracheal vessel passes through it to the globe, where 
it breaks up into many branches which ramify in the tissue, 
