314 MODERN CLASSIFICATION OF INSECTS. 
is greatly enlarged, the metathorax being again reduced in size. 
The prothorax bears upon its upper side a pair of organs, especially 
characteristic of the order, namely, a pair of scales covered with 
hair quite distinct from the wing-covers (tegule), which Kirby and 
Spence call patagia or tippets, but which have been overlooked by 
all other authors except Chabrier, who first discovered them, or else 
confounded them (as by Burmeister, Translation, p.'77.) with the true 
tegulz: they are described as vesicles appearing full of liquid and 
of air, and are placed at the sides of the pronotum (fig. 105. 6., being 
the two transverse oval parts figured in the transverse piece 
succeeding the head); the prothorax,is often differently coloured to 
the remainder of the thorax: thus, in the large Papilionide, it is 
marked with conspicuous red spots. The mesothorax is furnished at 
the sides with a pair of large triangular scales called pterygodes by 
Latreille, paraptera by MacLeay, or tegule by Kirby and Spence, 
affixed at the base of the anterior wings on the upper side, often 
clothed with hairs of a different colour to the rest of the mesonotum 
(as in Arctia villica). The form of these organs is very variable, 
giving to the thorax a diversity of appearance : thus, in the genus Cu- 
cullia (belonging to the family Noctuide), they are very large, and 
the thorax is pushed forwards, forming a sort of hood over the head ; 
whilst, in Xylina, they are more elongated; and give to the sides of 
the thorax an elevated appearance, with the centre depressed. In 
Jig. 105.6., the right parapteron is shaded with longitudinal lines, 
the left one being removed to show the mesothoracic spiracle. The 
scutellum of the mesothorax occupies the hind part of this segment. 
The metathorax is a shorter transverse piece composed of an anterior 
and posterior piece, with two lateral ones of a triangular form, the 
apices of which meet in the middle of the metanotum. This part 
is dotted in fig. 105.6.; its small anterior portion I have considered 
as the preescutum of the metathorax, the two lateral pieces as con- 
jointly forming the scutum and the posterior part as the scutellum. 
(Griffith, An. Kingd. pl. 121. three upper figures, Saturnia pavonia 
major.) The segment immediately following this dotted portion has 
a membranous wrinkled appearance in Cossus ligniperda (Lyonnet, 
Posth. Mém. pl. 46. f. 4. segment 4.), which might lead to the idea 
that it was analogous to the semicircular membrane represented in my 
Jig. 72.1. and 2.t, and considered (p. 92. note anté) as analogous to 
the funiculus of the petiolated species ; but on examination of other 
