THE THORACIC MUSCLES OF THE COCKROACH 

 PERIPLANETA AMERICANA (L.) 



By C. S. CARBONELL 



Laboratoria de Entomologia, Direccion de Agronornia, Ministerio 



de Ganaderia y Agricultura de la Republica Oriental 



del Uruguay 



(With Eight Plates) 



CONTENTS 



Page 



Introduction i 



I. Discussion of the mechanism of motion 2 



The cervical and ventral muscles 2 



The form of the thorax and mechanism of the legs 3 



Coxal, muscles 5 



Trochanteral muscles 6 



The dorsal and wing muscles 7 



Dorsal longitudinal and oblique muscles 7 



Muscle of the basalar plate 7 



Muscle of the subalar plate 8 



Pleuro-alar muscle 8 



Muscles of the anterior notal wing process 8 



II. List of the thoracic muscles 8 



Neck and prothorax 8 



Mesothorax 12 



Metathorax 16 



Literature cited 20 



Abbreviations used on the figures 20 



Explanation of plates 21 



INTRODUCTION 



The cockroach has been the subject of many works in entomology. 

 Its external anatomy is well known, and the insect is commonly used 

 for experiments in insect physiology and investigations on insecticides. 

 However, little has been published on its internal anatomy. Consider- 

 ing that a better knowledge of its anatomy could be useful to physiolo- 

 gists, economic entomologists, and anybody who uses the cockroach 

 for experimental work, R. E. Snodgrass, who directed this research, 

 proposed the musculature of the thorax as a theme. 



It was found, while working on this subject, that the thoracic mus- 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 107, NO. 2 



