THE SKELETAL MUSCULATURE OF THE BLUE CRAB, 

 CALLINECTES SAPIDUS RATHBUN 



By DORIS M. COCHRAN 



Assistant Curator, Division of Reptiles and Batrachians 



U. S. National Mtiseum 



CONTENTS 



Page 



I ntroduction 2 



Part I. The muscles of the trunk and its appendages 3 



The trunk 3 



The eye 6 



The retractor muscles of the eye 8 



The appendages 9 



The first antenna (antennule) ii 



The second antenna 13 



The mandible 15 



The first maxilla 19 



The second maxilla 21 



The first maxilliped 25 



The second maxilliped 28 



The third maxilliped 31 



The pereiopods 34 



First pereiopod 38 



Second pereiopod 39 



Third pereiopod 41 



Fourth pereiopod 43 



Fifth pereiopod 44 



The pleopods 46 



The male 46 



The female 48 



The skeleton 49 



The general structure of the crustacean appendage 53 



Part II. The ossicles and muscles of the stomach 60 



Ossicles of the stomach 61 



Ossicles of the " gastric mill " 61 



Cardiac " supporting ossicles " 64 



Pyloric " supporting ossicles " 66 



Muscles of the alimentary system 68 



Extrinsic muscles 68 



Intrinsic muscles 72 



Abbreviations used on the figures 74 



References 74 



Smithsonian Miscellaneous Collections, Vol. 92, No. 9 



