20 SPHINGIDiE. 



It is very large in Macroglossum and is smallest in the 

 Chcerocampin^e . 



Below the pilifer close to the tongue on each side is a short 

 process which is the remnant of the maxillary palpus (mxp). 

 It is in most cases densely clothed with long white scales. The 

 size of the vestigial maxillary palpus is not constant in the 

 family, nor has the palpus always the same shape. The 

 transverse arched strip of chitin between the labial palpi 

 is the mentum. 



The proboscis, or tongue, is formed by the first pair of 

 maxillae, and consists of two halves closely applied to each 

 other. Each half is concave on the inner side, and bears 

 at the inner edge a very dense fringe of cilia. The sucking - 

 tube itself, formed by the two halves of the glossa, is closed 

 above by the fringe, the cilia of which are fused together 

 to form a membrane. Among Sphingidje we find the longest 

 tongue of all insects, but it varies from 25 cm. in Cocytius 

 to 2 mm. in some Polyptychus . 



The palpus (fig. 7 G), if not reduced, is large, broad in 

 lateral aspect, closely contiguous to the head, and has a short 

 third segment. A palpus like this does not occur outside 

 the family. There are always three segments ; the third is, 

 however, nearly always very short and concealed in the 

 scaling of the second, projecting as a little knob. 



The first segment is the longest as a rule, and is curved, 

 lying along the eye. The inner surface is more or less regularly 

 annulated or wrinkled, flattened or slightly convex, or some- 

 what concave. It is naked, except the edges, with some 

 long hair-like scales ; or it is more or less loosely scaled for 

 the greater part. A character of the greatest importance 

 in the classification of the Hawk-Moths is found at the base 

 of the first segment — that is, a patch of variable size of short 

 (and doubtless sensory) hairs (a), which is always present 

 in one section of the family, excepting a few reduced forms, 

 and equally constantly absent from the other section. This 

 basal patch is found in butterflies, and is of wide occurrence 

 in moths. 



A peculiar modification of the first segment is found in 

 Megacorma and in a great number of Chcerocampin^e. There 

 is at the apex of the segment, ventro- laterally, a space 

 devoid of the ordinary scaling, being either quite naked 

 or clothed with a few long hair-like but flat scales. The 

 scaling around this naked space, which is often somewhat 

 concave, is more or less regular, especially ventrally, and, 

 surrounding the naked space, forms a kind of cavity (fig. 5E,#r). 



The second segment undergoes many modifications in 

 shape ; it may be subcylindrical, quadrangular, triangular, 

 ovate ; it may be longer or shorter than broad, or square. 



