- Diagram of morphological rela veloped mouth, gut and tions of Rotifera.
The standing of the Trichoptera in a position almost ancestral to the Lepidoptera is one of the assured results of recent morphological study, the mobile mandibulate pupa and the imperfectly suctorial maxillae of the Trichoptera reappearing in the lowest families of the Lepidoptera.
Considering the wide differences between the two groups in the size and external characters, and in the mode of life, including the mode of feeding, it is indeed surprising that in every important organ the two groups should show a fundamental morphological identity.
This has had a most important effect on the development in recent years of morphological anatomy.
The explicit adoption of this point of view has had the effect of clearing up and rendering definite the older morphological doctrines, which for the most part had no fixed criterion by which they could be tested.