264 Iiitroduci'ton to the Synopsis of the Acrididce. 



names : as, mh-gcaital lamina, . sjih-anal plate. In some genera and 

 species (Tnjxalis, J/e.sop.?,.some Opomala, etc.) the tii) is entire, while 

 in others it is notched. 



The pre-anal lamina, or super anal plale, is the triangular piece 

 which in both sexes lies over the anal aperture. 



The ovipositor of the female consists of four corneous pieces, two of 

 which curve upward and two dow^n ward, usually called the valves; 

 but Lacaze-Duthiers, who has made the genital organs a special study, 

 applies different names to the separate pairs, thus : the upper pair are 

 his episfernites, because they are above the little central piece, which 

 he considei-s the representative of the ninth sternite ; the lower pair 

 are his tergorhuhdites. 



Dr. Packard says: "The ovipositor, with its accessory pieces, con- 

 sists of a sub-genital plate formed by the seventh sternite ; the ninth 

 segment is complete, and the blades (tergo-rhabdites) composing the 

 ovipositoi- consist of three secondary pieces united together between 

 them." 



Internal Structure. 



• 



The nervous system, according to Leon Dufour, consists of a double 

 nei-vous chord, extending from the head to the tip of the abdomen 

 aluiig the lower part of the body, expanding at various points into 

 ganglia, which emit a greater or less number of branches to the right 

 and left. These ganglia are classed in three groups, according to the 

 part of the body in which they are situated — cephalic, thoracic, and 

 abdominal. The cephalic ganglion is the largest of the number, and is 

 deeply emarginate in front, giving it the appearance of being somewhat 

 bilobed ; in Tryxalis this feature appears to be most strongly marked. 

 In each of the thoracic divisions there is a ganglion, that of the meta- 

 thorax presenting the largest number of branches. 



The abdominal ganglia, of which there are some six or seven, are all 

 small, except the last, which is next in size to that of the head, emitting 

 to each side three important branches, connected, doubtless, with the 

 o-enerative organs. This system is more prominently developed in the 

 Acrididce than in any other family of the order, which has induced 

 Leon Dufour to give them the highest rank in the order. 



The digestive system consists of an alimentary canal, extending 

 almost direct from the mouth to the extremity of the abdomen, which 

 is divided bv constrictions into four apartments or divisions. The first 

 {ccsophagus) is somewhat inflated in its posterior half, giving it a sub- 

 conical shape, and is contained in the thorax. The ^yroventriculus 

 proper, which is formed in other families of this order, is wanting- in 



