( Ixxiii ) 



of a sensory character, the metaiiotnm occasionally taking part in the peculiar 

 structures. The Sphingidae have nothing of the kind, but possess other 

 specialisations in the abdomen, of which an armature consisting of spines is 

 the most notable one. The spines stand at the edges of the segments, and are 

 found on segments 2 to 8 in the c? and 2 to 7 in the ? . The dorsal spines 

 are stronger than the ventral ones ; the latter are often very weak, while the 

 former are strong ; or the ventral ones are only vestigial or are absent, while 

 the dorsal (ines are nuinerons. The longest spines are on the seveiitli tergite. 

 We find three main types, illustrated by PI. LXII. f. 0. lO. 11. 



The most fre(jnent type is represented by f. lo. Here we have several rows 

 of elongate, flattened spines, those of the proximal row being (as is always the 

 case) the shortest, and those of the last row the longest, so that the upper 

 ones cover the next only j)artly. The spines of this type vary in tiie different 

 species (resp. genera) from being very strong {Phryxta lineata ; Atemnora) to 

 being very weak, disappearing in some Ambulicinae altogether, or rather 

 developing all into scales {Lijcosphingia ; Cressoiiiu ; Langki'). Where the 

 spines are weak, the skeleton of the segments is also weak. The reduction 

 in the degree of chitinisation of the spines is generally accompanied by a 

 decrease in size, and often by an increase in number. In some instances 

 weak spines are distributed all over the tergites, this being due to the scales 

 of the under layer having become spiniform {AmhitUciiiae ; Mdvamhn ; Clnnis : 

 etc.). Where the spines are longer, more conical, and more strongly chitinised, 

 their number is generally smaller (Gnci/tina, for instance). This variable type 

 is found in all subfiimilies, the strongest reduction of the spines occurring in 

 Acherontiinae and Ambulicinae,. 



In the second type, represented by PI. LXII. f. 11 the sjiines are similar 

 to those of the strongly chitinised form of the first type, except in the spines 

 of the first row being short and rounded. The spines are all flat, black and 

 glossy, being very strongly chitinised. The type is very constant in itself, 

 and there are no intergradations between it and the preceding, except on the 

 proximal steruites. This kind of spination makes the abdomen smooth and 

 slippery, the sjiiues lying very closely upon the following segment. The 

 spines of the sternites are the same as those of the tergites, only the 

 proximal ones of the proximal sternites being a little longer. The type is 

 confined to Sesia and allies and MacroyloMum and allies — i.e. to the most 

 s]jecialised genera of Sesiinae and I'hilampeliiiae. The basal sternite (= sternite 

 of second segment) is sjiinose in the species with this type of s{)ination 

 (PI. LXIII. f. 2). 



In the third type, which is connected by intergradations with tlie first, 

 there is only one series of sjiiues (PI. LXII. f. 0), which stand often well 

 apart, and are long, conical, and very strong. The form of this type without 

 any small spines occurs only on the last tergites ;' on the more proximal tergites 

 and on the jwsterior sternites smaller spines appear between the long ones, 

 while on the basal segments the spines are all short and flat, the uniserial 



