MORPHOLOGICAL ADAPTATION IN INSECTS — GRANDI 205 



conspicuous tegumental apodemata (the dorsal, longitudinal, and 

 submedian apodemata may converge again posteriorly or are sub- 

 parallel) ; the palate tends to differentiate anteriorly more or less 

 conspicuous hairlike processes; the gnathites are little modified; the 

 segments of the body are more or less considerably protruding on 

 the sides ; the thoracic and abdominal legs are generally involuted, 

 subatrophied, or have disappeared and are often replaced with 

 ambulacral areolae (the thoracic legs are the first to disappear), and 

 so on. These modifications (partly resulting from the involution, 

 rudimentation, and atrophy of organs, partly from the deformation 

 of preexistent organs or from the development of new organs) do 

 not seem to be always correlated and are considered to represent a 

 complex of not very important "adaptations" by which a larva is able 

 to live, move, and feed within vegetal tissues of a particular type 

 without (it might be said) the hindrances of a cumbersome body 

 structure. Instead, if we give attention to other Lepidoptera Hetero- 

 neura, Dithrysia and miners, too, such as the Phyllocnistidae belong- 

 ing to the genus Phyllocnistis ZelL, and Gracilariidae belonging to 

 the genera Gracilaria Zell., Acrocercops Wallengr., Oecophyllemhius 

 Silv., Lithocolletis Zell., etc., we are in the presence of hypermeta- 

 morphic insects having a first larval phase with a generally plasmoph- 

 agous diet, and morphologically very much modified, and a second 

 type which may be cruciform, histophagous, endophytic or ectophytic, 

 or a "sui generis" astomous, aphagous form which has the sole func- 

 tion of constructing the cocoon for the metamorphoses. It is neces- 

 sary briefly to examine these larvae. 



In the ultraspecialized larvae of the first phase the body is flattened ; 

 the head capsule is prognathous, very greatly flattened, sclerotized at 

 the side edges, crossed by strong apodemata, of which the submedian 

 longitudinal ones diverge backward, posteriorly and dorsally con- 

 tinued with two large laminae, which are invaginated within the 

 thorax ; ocelli are very much reduced in number and size ; the mouth 

 parts are deeply transformed (the labium and prelabium have been 

 transformed into two wide, transverse, superposed laminar organs, 

 between which the very flattened mandibles move in the horizontal 

 plane ; the maxillolabial complex without lobes, palpi, and seri- 

 ciparous papilla is blended and sclerotized and, having become an 

 integral part of the head capsule, in correlation with prognathism, 

 closes it underneath like a throat) ; the tentorium is displaced back- 

 ward ; the body segments projecting laterally are separated by deep 

 constrictions (the loth urite is more or less exceptionally lengthened 



