610 THE SENSES AND SENSORY ORGANS. 
Lee, in 1885 [299], investigated these organs in the Blow-fly, 
and came to the conclusion that the chordotonal organs of the 
halter are not in relation with the pores of the basal and scapal 
plates, but form a special organ. 
According to Lee, the basal papillae open externally by a 
narrow funnel which is sometimes round, sometimes slit-like ; 
at the bottom of the funnel is a cushion, which is perforated 
by a fine fibril given off by a subjacent bipolar ganglion cell. 
In favourable objects Lee claimed to have seen a very fine, 
often bent, hair projecting from the cushion through the 
funnel. The scapal papilla were regarded by Lee as similar 
to the basal papillae, but more difficult to investigate, owing to 
the more complex sculpturing of the cuticular layer. 
Weinland [800] describes the scapal papillae as opening 
externally by a slit which communicates with a cavity con- 
taining a cone-like nerve terminal. The basal papillae differ, 
however, according to him, in having a kind of chitinous 
operculum closing the orifice of the cavity which contains the 
nerve terminal. I have made the most careful and repeated 
examination of the organs in question, and although I have 
seen all the appearances figured by Weinland at different times, 
I do not think his conclusions correct. Other appearances 
which are frequently seen are quite inconsistent with the view 
he takes, and he has, I believe, fallen into error in mistaking 
oblique sections of fragments of the halter for sections vertical 
DESCRIPTION OF PLATE XLIII. 
The halter and tympanic organ of the Blow-fly. 
Fic. 1.—A longitudinal section of the scabellum and part of the scape of a halter. 
b, basilar membrane separating the canal of the scape from the chordotonal 
organs; ¢, Superior, and ¢y, inferior canal of the scape ; c#, Lee’s chordotonal 
organ ; cv, cupola; 7, nerve; ¢, tubercle at the base of the halter, seen with a 
iy oil immersion objective. 
Fic. 2.—A transverse section through the scabellum. @, anterior ; s, superior, and 
jp, posterior surface ; c, a portion of the inferior canal; ¢ 4, a portion of the 
superior canal; ch, small chordotonal organ ; 7 to my branches of the nerve ; 
wv, an inflection of the external integument, seen with ay oil immersion objective. 
Fic. 3.—The right tympanic fissure of a Blow-fly; ¢, sclerite in the floor of the 
fissure ; f, propterygium of the wing; sy, squama or great wing scale ; sga, 
squamula ; ¢ s, tympanic sclerite in the upper part of the membrana tympani ; 
w, part of the wing ; 4, deltoid, and 7, tau of the wing. 
