MEINERT ON MOUTH-PARTS 45 
of the Diptera, he adopts Burmeister’s view that the labelle are homologous with 
labial palpi. None of the recent authors have concurred in this view. The 
three terminal lobes of the labium have been designated by Kellogg, who has 
given a very clear exposition of the mouthparts of the Nemocera, as, medianly 
the fused glosse, and, outwardly the paraglosse. This interpretation has been 
followed by Wesché and others. Other details, such as the attempts to find 
homologues of the components of the maxille and labium of mandibulate in- 
sects, can be passed over as purely hypothetical. 
All the authors who have endeavored to homologize the mouthparts of the 
Diptera with those of the mandibulate insects have, with one exception, agreed » 
as to the fundamental parts, the labrum, hypopharynx, mandibles, maxille, and 
labium. 
John B. Smith, in a paper published in 1890, took an entirely different view 
and defended this in a further paper which appeared in 1896. This interpreta- 
tion has been adopted in a recent popular book on mosquitoes. He used the 
mouthparts of certain highly specialized Hymenoptera and Coleoptera as a basis 
for his homologies. Smith found in Simulium, apically in the labrum, a pair of 
small dentate chitinous structures which he considered rudimentary mandibles ; 
these structures appear to be absent in all other nemocerous Diptera. He sup- 
posed, not only that the parts usually considered mandibles are maxillary, call- 
ing them lacinie, but that maxillary structures entered largely into the composi- 
tion of the labial sheath. The parts supporting the labelle are said to be part of 
the maxille, the subgalex, the labellee themselves the gale. The labium is rep- 
resented as a free piece, enclosed by the galeal structures, and the hypopharynx 
united with it. Smith’s work has been adversely criticized by the students of 
dipterous mouthparts and moreover bears clear evidence that it was based merely 
on rough dissections; only recently Leon, in a paper on Stimulium, discusses 
Smith’s homologies and points out the relationships of the parts in accordance 
with modern studies. 
Meinert developed views at variance with all the other students and did not 
believe that the mouthparts of the Diptera are homologous with those of man- 
dibulate insects. While his interpretation is in the main controverted by the 
histological work of Kellogg, it still seems of sufficient interest for a brief notice, 
all the more as it has been generally ignored. 
Like all other modern investigators Meinert recognized that generally the 
mouthparts of insects are homologous with the legs of the body and that, there- 
fore, they are the exponents of distinct metameres. He demanded, however, 
that to identify them with these, and those of the different orders of insects with 
each other, something sufficiently characteristic should be in evidence and he 
says: 
“I find this in the presence of a metamere and in the free jointing of the ex- 
ponents to the under side of such a metamere, and according to this criterion 
I test, whether the mouth-parts (that is the mouth-parts proper, the paired ones) 
are homologous with appendages of the body on the one side, or among them- 
selves on the other.” 
