16 



be called a carina. In some cases the sides slope upward to the median 

 carina, leaving no lateral carina or angle (as in Tropidolophus^ PL, Fig. 1, 

 and Tropidacris) ; in other cases (as in Mesops, Boopedon, PI, Fig. 11 ; some 

 species of Opomala^ &c.) the pronotum is cylindrical. The lateral carinee 

 afford important generic and specific distinctions, by their relation to each 

 other, shape, &c., as to whether they are parallel or convergent, straight or 

 curved, continuous or interrupted. The front margin of the pronotum seldom 

 presents any angular points, being usually obtusely rounded or truncate; but 

 the posterior extremity generally extends backward, in a rounded or angular 

 form, upon the base of the elytra ; in a few cases (as Chrysochraon, and some 

 species of Pezotettix in which the elytra and wings are wanting) the posterior 

 margin is truncate. The posterior lateral margins are the hind margins run- 

 ning down from the extremity of the dorsum to the posterior angle of the 

 sides. 



The body of the pronotum is generally divided into four lobes by three 

 transverse sutures or impressed lines (these are quite distinct in Fig. 2 of the 

 plate) ; the lobe, or portion next the head, is the anterior lobe, the hindmost 

 one the posterior lobe, the other two the middle lobes. In many species the 

 two anterior impressed lines are indistinct or wanting, but the posterior one 

 is nearly always present, except in the Tettigince. These hnes are sometimes 

 designated by the numbers 1, 2, and 3, beginning with the front one and 

 counting backward. 



The general form of the pronotum affords very important characters ; 

 sometimes the width is uniform and the sides are parallel; sometimes they 

 diverge posteriorly ; at other times they approach each other in the middle, 

 in which case the pronotum is said to be constricted, but this term applies 

 only when the narrowest point is between the extremities. Its surflice also 

 varies — is smooth, punctured, rugose, or tuberculate.. 



The mesonotum and metanotum are hid by the pronotum and the wings, and 

 are not used in descriptions except in the case of a few wingless species of 

 Pezotettix. 



The prosterrium, or under side, of the prothorax is short, and is either 

 smooth — that is, it is without either tubercle or spine — or it is furnished witli 

 an obtuse tubercle, or a conical spine, called the prosternat spine (PL, Fig. 8, 

 sp^. The species furnished with this spine are said to have the prosternum 

 armed or mucronate {Opomala, Mesops, Romalea, and all of the group Acridini) ; 



