Introduction to the ^Tjnopsis of the Arridida'. 2fio 



some eight ov nine corneous rings or segments, which decrease m siz-' 

 toward the apex (though in some genera, HBCaloptenus and Pezotettix, 

 the terminal segments of the male are somewhat enlarged). The typi- 

 cal number of segments of the abdomen, according to Lacaze-Duthicr- 

 (who is followed by Dr. Packard, in his "Guide to the Study of 

 Insects"), is eleven. But if we count the dorsal segments in the 

 female, to and including the point where the upper and lower plates 

 separate for the extrusion of the ovipositor, there are really but nine. 

 It is true that the ninth, wdiich folds over the upper valves of tlic 

 Dvipositor, shows two transverse folds besides the terminal piece over 

 wliich the pre-anal -plate rests ; each of these is counted as a segment 

 by Lacaze-Duthiers, thus making the eleven ; but the incisions mark- 

 ing these folds are incomplete, not reaching the lower margin of the 

 plate. Between the second of these folds and the terminal piece on 

 each side issues a short process, not extending beyond the apex of this 

 piece ; these appendages are the cerci. 



Fischer says the abdomen in both the male and female consists of 

 nine distinct segments. Westwood remarks that the inferior surface 

 of the abdomen in the male consists of eight segments, but only of* 

 seven in the female. Lacaze-Duthiers says the sub-genital is formed 

 by the seventh sternite (ventral scgntent) ; if we consider the piece . 

 which projects forward into the posterior margin of the metasternum 

 as belonging to the venter, and as representing the first sternite, which 

 I am inclined to think it does, then there are eight ventral segments 

 (steruites) in the female, and nine in the male. 



Each abdominal ring is, or is supp>osed to be, composed of six pieces, 

 soldered together, three to each lateral half; but for all the purposes 

 of the present work, w^e may consider them as composed of but tv.o 

 l)ieces or plates, an upper or dorsal plate, called the tergite or dorscd 

 !>egment, and the lower plate, called the sternite or ventral segment. The 

 under surface of the abdomen, as a whole, is the venter. 



On each side of the basal segment is a large cavity, either of a semi- 

 orbicular or lunar shape, which is closed on the inside by a very 

 slender skin of a whiteish color. This is the tympanum, and is sup- 

 posed by some entomologists to have a certain influence upon the act 

 .of striduiation, while others believe it to be the organ of hearing; the 

 latter appears to be the more generally received opinion at present. 



The apex of the ventral portion in the males curves uj)ward, some- 

 what in the form of the prow of a vessel ; this curved portion, in some 

 species appears to form the last ventral segment (sternite), but m 

 others a transverse impression is seen, separating the apical surface 

 from the rest. This apical portion has received several ditfcrent 



