THE ABDOMINAL MECHANISMS OF A GRASSHOPPER 



By R. E. SNODGRASS 



Bureau of Enfoinology and Plant Quarantine, U. S. Department of Agriculture 



CONTENTS PAGE 



Introduction i 



I. General structure of the abdomen 2 



Characteristic features of the abdomen of Acridoidea 3 



Relation of the abdomen to the thorax 8 



The abdominal spiracles 11 



The tympanal organs 12 



The cerci 15 



II. The abdominal musculature 16 



Muscles of the first segment 16 



Muscles of the second segment 18 



Muscles of the third segment 20 



Muscles of the eighth segment 24 



Muscles of the ninth segment 26 



Muscles of the tenth segment 29 



Muscles of the eleventh segment 31 



The transverse muscles 31 



III. The diaphragms and the dorsal blood vessel 31 



IV. The proctodaeum 34 



V. The ovipositor and associated structures 37 



Structure of the ovipositor 37 



The female genital chamber and the spermathecal opening 45 



Development of the ovipositor 48 



Oviposition 54 



VI. The external male genitalia 61 



General structure of the m.ale genitalia of Acridoidea 61 



Copulation, and insemination of the female /i 



Examples of the male genitalia of Acrididae 73 



Abbreviations used on the figures .- . . 86 



References 87 



INTRODUCTION 



This paper on the abdomen of Acridoidea is intended to follow 

 sequentially an earlier paper in the same series entitled " The Thoracic 

 Mechanism of a Grasshopper" (Smithsonian Misc. Coll., vol. 82, 

 no. 2, 1929). Hence it will be observed that the numerical designation 

 of the abdominal muscles continues from that of the thorax. 



Smithsonian Miscellaneous Collections, Vol. 94, No. 6 



