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PROGNATHISM AND HYPOGNATHISM IN INSECTS

Published online by Cambridge University Press:  31 May 2012

E. M. Walker
E. M. Walker
Affiliation:
University of Toronto
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Extract

It is generally admitted that the primitive position of the Arthropod mouth and its associated appendages is ventral, this position being evident in the early embryonic stages of all groups and retained in the adult stages of many forms, particularly among the Crustacea. It is by no means to be inferred from this, however, that this ventral position of the mouth is the primitive one in the Insecta as a class. Great variability exists among insects in the postembryonic stages in respect of this feature. The mouth and jaws are usually directed more or less forward and downward but vary from a wholly anterior position to a definitely ventral one, or they may even be directed posteriorly.

Type
Articles
Information
The Canadian Entomologist , Volume 64 , Issue 10 , October 1932 , pp. 223 - 229
Copyright
Copyright © Entomological Society of Canada 1932

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References

REFERENCES

Crampton, G. C. 1921. The sclerites of the head, and the mouth parts of certain immature and adult insects. Annals Ent. Soc. Am., 14, 65–103, pls. 2–8.CrossRefGoogle Scholar
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Crampton, G. C. 1932. A phylogenetic study of the head capsule of certain orthopteroid, psocoid, hemipteroid and holometabolous insects. Bull. Brooklyn Ent. Soc., 27, 19–55, pls. 4–8.Google Scholar
Snodgrass, R. E. 1928. Morphology and evolution of the insect head and its appendages. Smiths. Misc. Coll., 81, 1–128, 57 figs.Google Scholar