8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



having a small, simple lacinia and a galea, and a long 5-segmented 

 palpus. A detailed comparative description of the mouth parts of 

 several micropterygid species is given by Issiki (1931), but he says 

 nothing of the food or feeding habits of the insects. According to 

 Tillyard (1923) the mandibles of Sabatinca "work in conjunction 

 with the epipharyngeal and hypopharyngeal brushes and the triturat- 

 ing basket of the hypopharynx as grinders of the minute pollen grains 

 or other fine vegetable matter which form the food of the imago." 

 Hannemann (1956) says the long flexible maxillary palpi are used for 

 bringing the food into the mouth. 



If the mandibulate progenitors of the Lepidoptera fed on pollen, 

 they had easy access to nectar, their problem being how to obtain it 

 from the depth of the flower corollas. If, then, some fortunate muta- 

 tion happened to lengthen the maxillary galeae, the latter may have 

 enabled their possessors to get a taste of nectar. The next step in the 

 evolution of a maxillary proboscis is seen in the modern Eriocraniidae, 

 in which the galea of each maxilla is much elongated, curved, and 

 grooved on its inner surface (fig. 3 B), while the lacinia is entirely 

 suppressed. According to Busck and Boving (1914) in Mnemonica 

 auricyania the galeae have marginal serrations that serve to connect 

 them with each other. In the Mnesarchaeidae the galeae are still more 

 lengthened (C), and the maxillary palpi are reduced to three small 

 segments. From the condition in these two primitive lepidopterous 

 families it is but another step in the same direction to the long, coiled 

 proboscis typical of the other Lepidoptera (fig. 3E), in which the 

 base of the maxilla (D) retains the form it has in the eriocraniids. 

 Along with the development of the proboscis the mandibles underwent 

 a reduction until they became functionless vestiges or disappeared 

 altogether. From an early stage in their evolution, therefore, the 

 Lepidoptera became entirely liquid feeders. 



The fully developed proboscis of modern Lepidoptera is a truly 

 remarkable instrument. When not in use it remains tightly coiled 

 beneath the head, but it can be straightened out to its full length for 

 insertion into flowers to serve as a nectar conduit. A detailed study 

 of the structure and mechanism of the proboscis of Pieris brassicae 

 has been made by Eastham and Eassa (1955), in which they critically 

 review and correct certain ideas on how the proboscis works expressed 

 by earlier writers. 



A proboscis alone could not serve for the ingestion of liquid food ; 

 a sucking apparatus must have been developed along with the evolu- 

 tion of the proboscis. In Micropteryx it is shown by Hannemann 

 (1956) that the slender oesophagus opens directly from the preoral 



