138 



REPORT OF STATE GEOLOGIST. 



joint is much shorter and carries a smaller pad. Tlie third joint is 

 long and slender, with two curved, pointed claws or "ungues" (un); 

 between which is a concave sucking disk or pad, known as the "pul- 

 villus" (pv). In some families of Orthoptera the tarsus is made up 

 of four or five joints instead of three. 



The Abdomen. 



The abdomen or hind portion of the body of the locust (See 

 Figs. 2 and 4) is composed of ten more or less complete seg- 

 ments, so united as to be movable in a small degree. Each segment 

 is composed of two parts, a "tergum" or upper portion, and a 

 "sternum" or under piece. The tergum is crested or bent in the 

 median line to form a ridge, the two sides, sloping downward, being 

 known as "iergite^." The sternum of the first or basal abdominal 

 segment is united firmly to that of the metathorax. The tergites 

 of this segment, in the locust, each contain a large opening closed 

 by a membrane, the "auditory organ" or ear. However, the ears of 



many Orthoptera are borne upon 

 the basal portion of the front 

 tibiffl. Eight of the abdominal 

 segments of the locust have a 

 small opening on the lower mar- 

 gin of each "tergite." These are 

 "spiracles" or external openings 

 of tubes which serve as air pas- 

 sages. The ninth and tenth ab- 

 dominal segments of the locust 

 are more or less modified in both sexes. The abdomen of the female 

 ends in a double pair of short curved horny plates, known as the 

 "valves of the ovipositor." In the other families of Orthoptera in 

 which the ovipositor is visible, these plates vary greatly in form and 

 size. The valves in the female locust are used in forcing the earth 

 aside, thus forming a pit in which the eggs are deposited. Between 

 and hidden by them is the ovipositor proper. 



The ventral portion of the last abdominal segment of the male 

 locust is a large, upcurved, spoon-shaped piece known as the "suh- 

 geniial plate." Attached to the tergum of the next to the last seg- 

 ment are a pair of appendages known as the "cerci." In the male 

 locust these are unjointed, and in the different species vary much in 

 size and shape, affording valuable characters for classification. In 

 many of the other families they are jointed, and more or less hairy. 



Fig. 13. Auditory organ? or ears— (A), of a 

 locust; (B), of a katydid. (After Lugger.) 



