642 DESCRIPTIONS OP PLATES. 



and at the anterior ridge of which the hook b hangs by two joints. Fig. 7., 

 Central division of the prehensile organ, a a, The processes, b, The hook 

 between them raised. Fig. 8, First division of the same organ, consisting of 

 the anterior pieces, a a, which articulate at d d with the posterior ones, b 6, 

 and the hooks c c. Fig. 9, Apex of the abdomen of a male Libdlula. 

 Fig. 8, 9, 10, The same ordinal joints of the abdomen, a, The aperture to the 

 sexual organs. 



PI. XII. [No. 1,] Skeleton of Cimbex variabilis. Fig. 1, Lateral view of the 

 thorax, a, Tegula which covers the first thoracic spiracle, d, Patagium 

 analogous to the anterior wing of the scapula, c, Scutellum. (3, Second 

 spiracle. Fig. '2, View of the thorax from above. yy, Cenchri. Fig. 3, 

 Mesonotum alone, a, Prophragma. d d, Patagia. c, Scutellum. Fig. 4, 

 Prosternum seen from behind, to show the internal processes a a. b b, Cavities 

 of the coxae. Fig. 5, The same from the side. Fig. 6, Mesosternum with its 

 lateral ascending wings. a a, Internal process divided into two points. 

 b b, Cavities of the coxa?, c, Hook-shaped process, which originates from the 

 side of the sternum, and serves the muscles of the coxse for insertion. 

 [No. 2,] Skeleton of Scollaflavifrons. Fig. 1, Thorax from above, d d, Patagia. 

 c, Scutellum. /3 /3, Second spiracles. Fig. 2, The same from the side, 

 a, First spiracle. 0, Second, d, Patagium. c, Scutellum. Fig. 3, The 

 same from beneath. * Aperture through which the tendon passes which holds 

 the abdomen. Fig. 4, Metanotum with the process to which the muscle is 

 attached, which, with the tendon proceeding from it, holds the abdomen. 

 Fig. 5, The same from the side. Fig. 6, Prosternum from behind. 

 a a, Acetabulse of the coxce. b b, Internal processes. Fig. 7, Cavity, A, in 

 the metathorax, for the reception of the apex of the abdomen, a, Hole through 

 which the tendon passes, b b, Ball joints. Fig. 8, Cavity in the base of the 

 abdomen, which inserts itself in the cavity of the metathorax. a a, Sockets. 

 6 b, Ball joints, c, Process to which the tendon is attached. Fig. 9, First 

 segment of the abdomen seen from the side. a, Process to which the tendon 

 is affixed. b, Socket for the reception of the ball joint of the metaphragma. 

 c, Ball joint which is inserted in the socket of the metaphragma. 



PI. XIII. [No. 1,] Thorax of Methoca ichne-umonides,Lzt. Fig. 1, Thorax 

 seen from above. A, Pronotum. c, Scutellum. F, Metanotum. Fig. 2, The 

 same from the side. B, Prosternum. E, Mesosternum. G, Metasternmn. 0, Se- 

 cond spiracle. [No. 2,] Thorax of Myrmosa melanocephala, male. Fig. 1, 

 From above. Fig. 2, From the side, marked as above. [No. 3,] Superior view 

 of the thorax of Chrysis ignita. A, Pronotum. C, Mesonotum divided by 

 two furrows into three fields, c, Scutellum. d d, Patagia. F, Metanotum. 

 [No. 4,] Thorax of Cossus liynipcrda. Fig. 1, View from above, c, Mesonotum. 

 D*, Patagium. d d, Frenum. c, Scutellum. F F, Metanotum. K K, Coxiv 



