DESCRIPTIONS OF PLATES. 641 



b, The central petiole which is affixed to the anterior main nemire of the 

 wing. 



I J 1. XI. [No. 1,] Skeleton of Gryllotalpa vulgaris. Fig. 1, Prouotum from 

 above. Fig. 2, Prothorax from beneath, a a, The two stigmata which lie in 

 the membrane behind the prothorax. b, Aperture of the neck, being the 

 entrance to the prothorax. c, Posterior aperture, d d, Cavities for the coxa). 

 Fig. 3, Internal skeleton of the prothorax. A, Pronotum. B, Prosternum. 

 C, Descending keel of the pronotum, which divides into two furcating 

 lamellae, the anterior and posterior points of which are at EE and F F. With 

 the anterior ones, the T-shaped anterior distension of the sternum articulates, 

 and with the posterior ones, which again unite, the posterior apex articulates at *. 

 Besides which, two processes, D D, spring from the sides of the pronotum, which 

 meet at the anterior angles of the central carina near E E. A process, G, springs 

 on each side backwards from the posterior angles of the central carina, both of 

 which are retained by a bone upon which the crop rests, and which is connected 

 by muscles at * * with them. Fig. 4, Meso- and metathorax from above. 

 Fig. 5, Mcsosternum from the side, lying free internally upon the external 

 plate E, the point bending backwards. Fig. 6, The same from beneath with 

 the backwards directed processes, the points are cut off. Fig. 7, The mesonotum 

 seen from the front to exhibit the prophragma, in which, at , the aperture 

 to the aorta is found. Fig. 8, Lateral view of the meso- and metathorax. 

 |8, Stigma upon the limits of the meso- and metathorax. [No. 2,] Skeleton of 

 Gryllus migmlorius. Fig. 1, Head from beneath, with the aperture of the 

 mouth distended anteriorly to exhibit the radiating tentorium (c c c). 

 o a, Basal joints of the antennae, b b, The eyes. Fig. 2, Prothorax from front, 

 natural size, a a, The horny arch springing from the sides, which bow over the 

 aeetabuloe of the coxae. Fig. 3, Meso- and metathorax from above, with dis- 

 tended but cut-off wings, c c, Prophragma. Fig. 4, The same from the side. 

 a a, Rudiments of the base of the wings, c, Prophragma. /3, Second spiracle of 

 the thorax. Fig. 5, The same from beneath. Fig. 6, Mesothorax alone seen 

 from behind. C, Mesonotum. DD, Scapulae. E, Mesosternum. a a, Remains 

 of the wing, c, Mesophragma with the aperture p for the aorta, d d, Internal 

 ridges, which indicate the suture of the wings of the scapulae, e e, Horny arch 

 spanned over the acetabulae. [No. 3,] Skeleton of Libellula. Fig. 1 , Entire thorax 

 from above, with the remains of the wings. Fig. 2, The same from the side. 



c, The free prophragma. <3, Second thoracic spiracle. Fig. 3, The same 

 from beneath. Fig. 4, Prehensile organ upon the second and third ventral 

 segments of the male Libellula. a a, Two moveable books svhich encompass 

 the points * * of the processes b b. c c, Processes of the second division of 

 the prehensile organ, between which the hook d lies, e, Third division of 

 that organ. Fig. 5, The same from the side. Fig. 6, Third division of the 

 prehensile organ, consisting of a large swollen knob, a, which at d is excavated, 



