1918] Thoracic Sclerites of Dissosteira 359 



The Leg* 



The metathoracic coxa "cxs" is much larger than the coxae 

 of the other segments due to the greater development of the 

 hind legs for leaping, and tends to become longer than the 

 other coxae. The trochanter "tra" (Fig. 2) is greatly reduced, 

 and is more readily seen from the ventral (or mesal) surface. 

 The femur is greatly thickened for leaping, and is provided 

 with prominent longitudinal ridges on its inner surface. 



The Metasternum. 



The principal region of the metasternum is the basisternum 

 "bss" (Fig. 2) which interlocks with the mesosternum in front 

 of it, the narrow anterior region of the metasternum being 

 "dovetailed" between the mesosternal lobes "I2" and "I2." 

 The lateral wings of the basisternum largely make up the 

 sclerite "IS3" forming a pre-coxal bridge on either side of the 

 body, connecting the sternal with the pleural regions. The 

 antecoxal region "acs" is largely sternal in origin, and, with the 

 sternal sclerite "st," it forms an incomplete ring extending 

 around the base of the coxa anteriorly, so that these two 

 sclerites may represent a portion of the ring "pc" which com- 

 pletely encircles the base of the mesothoracic coxa. The f ureal 

 pits "fs" are retained in the metasternum, but the spinal pit 

 "SS2" of the mesosternal region has disappeared in the meta- 

 sternum. The metasternal lobes "I3" and "I3" are somewhat 

 smaller than the mesosternal lobes. In certain grasshoppers 

 the transverse distance between the two points "x" and "x" 

 of the metasternum is only half the distance between the points 

 "x" and "x" of the mesothorax {i. e., the mesosternal lobes are 

 "twice as distant" as the metasternal lobes) — a feature fre- 

 quently used in classification. The greater part of the region 

 between the metasternal lobes "I3" and "I3" is thought to be 

 an anterior "neck" of the first abdominal sternum which has 

 become wedged in between the metasternal lobes, although it 

 is rather difficult to understand how such a dovetailing process 



* Since the coxa of the metathorax is called the metacoxa, the tibia of this 

 segment is called the metatibia, etc., the tarsus of the metathorax should be 

 designated as the metatarsus; but since the designation metatarsus is sometimes 

 incorrectly applied to the basal tarsal segment of the prothoracic or mesothoracic 

 regions, it is preferable to designate the basal segment of the tarsus as the prae- 

 tarsus, or basitarsus, in all cases, if we are to avoid ambiguity. 



