THE PATAGIA AND TEGULAE 89 



rests upon the sternum ; the other is the epitnernm. To these pieces, 

 with the sternum in part, the legs are articulated (Fig. 89). 



Between the episterna is situated the breastplate or sternum, 

 which is very large in the more primitive forms, as the Orthoptera, 

 and is small in the Diptera and Hymenoptera. 



The episterna and epimera are in certain groups, Neuroptera, etc., 

 further subdivided each into two pieces (Fig. 102). The smaller 

 pieces,. hinging upon each other and forming the attachments of the 

 muscles of flight, differ much in shape and size in insects of different 

 orders. The difference in shape and degree of differentiation of these 

 parts of the thorax is mentioned and illustrated under each order, 

 and reference to the figures will obviate pages of tedious description. 

 A glance, however, at the thorax of a moth, fly, or bee, where these 

 numerous pieces are agglutinated into a globular mass, Avill show 

 that the spherical shape of the thorax in these insects is due to the 

 enlargement of one part at the expense of another ; the prothoracic 

 and metathoracic segments being more or less atrophied, while the 

 mesothorax is greatly enlarged to support the powerful muscles of 

 flight, the fore wings being much larger than those appended to the 

 metathorax. In the Diptera, whose hinder 

 pair of wings are reduced to the condition of 

 halteres, the reduction of the metathorax 

 as well as prothorax is especially marked 

 (Fig. 91). 



The patagia. On each side of the pro- 

 notum of Lepidoptera are two transversely 

 oval, movable, concavo-convex, erectile plates, 

 called patagia (Fig. 92). On cutting those of 

 a dry Catocala in two, thev will be seen to be 



J , Fio. 92. Prothorax of 



hollow. Cnoloakowsky states that they are ffeometra papiUoruiria : 



11, notuni ; ]>, pleura; fit, 



tilled with blood and trachea! branches; and sternum; j>t, patagia; m, 



. membrane ; f\ femur ; h, a 



lie went so far as to regard them as rum- i>ok bent 'backwards and 



. , beneath, and connecting the 



mentary prothoracic wings, in which view he pro- with tin- mesothorax. - 



, . After Cholodkovsky. 



was corrected by Haase,- who compares them 



with the tegulae, regarding them also as secondary or accessory 



structures. 



The tegulae. On the mesothorax are the tegiduz of Kirby (ptery- 

 fforJes of Latreille, parapt^ra of McLeay, hypopt&re or stpKiirmle), which 

 cover the base of the fore wings, and are especially developed in the 

 Lepidoptera (Fig. 90, A, f) and in certain Hymenoptera (Fig. 95, c). 



1 Cholodkowsky, Zool. Anz., ix, p. 615 ; x, p. 102. 



2 Zool. Anz., ix, p. 711. 



