MORPHOLOGY OF THE INSECT ABDOMEN 



PART I. GENERAL STRUCTURE OF THE ABDOMEN AND ITS 



APPENDAGES 



By R. E. SNODGRASS 



Bureau of Entomology 



U. S. Dkpartment of Aoriculture 



CONTENTS 



Introduction i 



I. The abdominal sclerotization 6 



II. The abdominal segments 14 



The visceral segments 16 



The genital segments i" 



The postgenital segments 19 



III. Tlie abdominal musculature 28 



General plan of the abdominal musculature 31 



The abdominal musculature of adult Pterygota 42 



The abdominal musculature of endopterygote larvae 48 



The abdominal musculature of Apterygota 56 



IV^. The abdominal appendages 62 



Body appendages of Chilopoda 65 



Abdominal appendages of Crustacea 68 



The abdominal appendages of Protura 70 



General structure of the abdominal appendages of insects 71 



The abdominal appendages of Collembola 72 



The abdominal appendages of Thysanura 74 



The abdominal gills of ephemerid larvae 77 



Lateral abdominal appendages of sialid and coleopterous larvae. ... 79 



The abdominal legs of lepidopterous larvae 83 



The gonopods 88 



The cerci (uropods ) 92 



The terminal appendages of endopterygote larvae 96 



Terminal lobes of the paraprocts 107 



Aforphology of the abdominal appendages loS 



Ablireviations used on the figures 122 



l\cferences 123 



INTRODUCTION 



The incision of the insect into head, thorax, and abdomen is in 

 general more evident in the cervical region than at the thoracico- 

 abdominal line ; but anatomically the insect is more profoundly divided 

 between the thorax and the abdomen than it is between the head and 



Smithsonian Miscellaneous Collections, Vol. 85, No. 6 



