58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



ments, it becomes a matter of necessity that there should be a com- 

 pensation from some source, and the expansion of the air sac would 

 take place automatically as in the inspiratory phase of breathing. The 

 observed filling of the stomach and air sacs with air, therefore, is 

 certainly not the active cause of the elongation of the abdomen ; it 

 seems much more probable that the inflation of these organs, fol- 

 lowed by a closure of the mouth and spiracles, serves to maintain 

 the extension of the abdomen when the valvulae of the ovipositor are 

 closed, since the latter has then no means of holding its position in 

 the earth. 



If we consider the several digging movements of the ovipositor con- 

 cisely enumerated by Fedorov, we can readily correlate them with mus- 

 cles in the motor apparatus. The preliminary closing of the valvulae is 

 effected by the muscles of the anterior intervalvula (fig. 17 D, C, 24"/, 

 273) ; the downward thrust must be produced by the protractors 

 inserted on the ends of the lateral apodemes (C, 2^6, 262) ; the open- 

 ing of the valvulae is the work of the powerful levators and depressors 

 (A, B, 2yi, 272) ; the twisting movements of the abdomen are ac- 

 complished by the transverse outer dorsal muscles between the suc- 

 cessive tergal plates (fig. 11 B, C). In addition to these muscles there 

 are the lateral retractors of the dorsal valvulae (fig. 17 C, 26^), evi- 

 dently capable of pulling the ovipositor back into the genital segments. 

 The muscular equipment of the ovipositor, therefore, is such that there 

 is no need to invoke any other mechanism to account for the operation 

 of the digging apparatus and the stretching of the abdomen than that 

 of the ovipositor itself. 



Species of Acrididae known to oviposit in dead wood or in the stems 

 of plants include Chloealtis conspcrsa Harris of North America, and 

 Chrysochraon dispar Germ, of Europe. Females of Dissosteira Caro- 

 lina are often to be seen along railroad tracks with the end of the 

 abdomen inserted into a decayed part of a tie, though, so far as 

 the writer knows, there is no record of their eggs being deposited in 

 such places. 



Chloealtis conspersa is said by Scudder (1874) to select for ovi- 

 position short sticks of decaying, charred, or pithy wood, but never 

 to choose upright pieces of timber. " The holes," Scudder says, " are 

 pierced at a slight angle to the perpendicular, away from the insect ; 

 they are straight for about a quarter of an inch, then turn abruptly and 

 run horizontally along the grain for about an inch. The eggs (from 10 

 to 14 in number) are almost always laid in the horizontal portion of 

 the nest." Blatchley (1920) also records observations on the wood- 

 excavating habits of the same species. One female he discovered in 



