DESCRIPTIONS OF PLATES. 639 



segment. S* S*, The second ditto. K K, Coxa; of the posterior legs 

 T T, Troclianters. Fig. 7, Anterior view of the mesosternura to exhibit the 

 two processes/, which form the fork, and between which the nervous cord lies 

 Fig. 8, Anterior wings of the scapula seen from the surface, b, The reflexed 

 margin which lies against the posterior wings. Fig. 9, Posterior wings of the 

 scapula seen from the surface, b*, The reflexed margin which lies against 

 the margin of the anterior wing, and forms the suture in which both meet 

 together. 



[No. 2,] Parts of the skeleton of Dyticus. Fig. 1, View of the internal portion 

 of the head after the removal of the upper integument. a a, The two ridges 

 which proceed from the throat and enclose the cerebellum between them. 



c, The tentorium or the transverse band of connexion between the two ridges. 



d, A second deeper-seated band, consisting of two halves, upon which the 

 anterior portion of the cerebellum rests, e e, Two hooked processes, which 

 proceed from the superior margin of the bands, and encompass the oesophagus 

 in front of the cerebrum. They serve for the insertion of small muscles which 

 retain the oesophagus, f f\ A horny ridge which runs beneath the frons from 

 one side of the head to the other, and to which the labrum is attached, g, The 

 labium, or, rather, its superior fleshy part, the tongue, h, A horny semicircular 

 bone, to which the tongue is attached ; it lies free in the flesh, and does not 

 come in contact with the integument of the head, b b, The orbits. Fig. 2, 

 The prothorax seen from beneath, b b, The omia. Fig. 3, The prosternum 

 from behind, a a, The jugularia which lie in the membrane of the neck, and 

 upon which the head revolves, b b, Internal processes of the prosternum which 

 encompass the nervous cord. Fig. 4, The omium seen from the surface. 

 b, The external surface, b*, The reflexed margin which lies against the 

 surface of the pronotum. Fig. 5, Prosternum from the side, b, The internal 

 processes. Fig. 6, Coxa), trochanters and femur of the intermediate leg, to 

 show the free articulating process, a, Audouin's trochantinus. Fig. 7, Meso- 

 and metathorax from above. Fig. 8, The same from beneath. Fig. 9, Meso- 

 sternum separated from the parapleura, with its internal processes. This gives 

 the most perfect representation of the vertebra of an insect. E is the body of 

 the vertebra whence the arches proceed which encompass the nervous cord. 

 b b are the transverse processes. a forms the processus spinosus, consisting 

 of two halves. At the superior transverse process of the body the scapula) 

 articulate ; they correspond to the articulating surfaces of the ribs in the 

 vertebrae. Fig. 10, Anterior wing of the scapula(D). Fig. 11, Posterior wing 

 of the scapula (D*). b, The reflexed margin which forms the suture with 

 that of the anterior wing. Fig. 12, The connate coxa) seen from the front to 

 exhibit the process springing from them. It ascends in a forwardly inclined 

 direction from the suture of both coxa 5 , and then divides into four processes, 



