
THE 
AMERICAN NATURALIST 


Vor. XXXVI. September, 1902. No. 429. 


THE DEVELOPMENT AND HOMOLOGIES OF 
TRE MOUTH PARTS OF INSECTS. 
VERNON L. KELLOGG. 
THE problem of the homologies of the mouth parts of insects 
is one long worked at by zoólogists. Since Savigny's first 
Statement in 1816 of his conclusions regarding the homologies 
of the arthropod appendages, this problem has been a favorite 
one with insect morphologists, and in this century of work 
much has been accomplished. There is a practically complete 
agreement as to the homologies of the parts of the biting 
mouth as this mouth is variously composed in the Orthoptera, 
. Coleoptera, Neuroptera, eż aZ, and a fair agreement obtains 
~ With regard to the interpretation of the homologies of some 
of the more modified kinds of mouth parts possessed by the 
Piercing and sucking insects. This is true especially of those . 
.. insects, like the Hymenoptera and the Lepidoptera, among which 



there are generalized forms showing the essential biting type 
(as with the sawflies among the Hymenoptera and Eriocephala 
_ and Micropteryx among the Lepidoptera), together with a series 
_ 9f gradatory forms leading plainly up to the highly specialized 
conditions exhibited by the higher members of these orders. 
