2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 92 



INTRODUCTION 



The need for detailed morphologic study of the muscles of crusta- 

 ceans is apparent upon making a survey of the very scanty literature 

 dealing with the myology of so diverse and important a suborder. The 

 taxonomy and the concurrent analysis of the external anatomy of 

 crustaceans have received a great deal of attention, and their physio- 

 logic reactions to stimuli have likewise been given a comparatively 

 large amount of study. The internal structure and particularly the 

 myology have been surprisingly neglected. 



Huxley (1880) made a now historic contribution in his book on the 

 crayfish, and his masterly dissections were unequalled for over a quar- 

 ter of a century. Then the German school of zoology at Leipzig began 

 a symposium on the crayfish, and the rechecking of the musculature 

 was undertaken by Walter Schmidt, who made a most thorough and 

 scholarly revision, in which he came upon several important points 

 which Huxley had failed to emphasize. 



The next complete myological study of a crustacean was published 

 by Alfreda Berkeley in 1928. Her study of the shrimp Pandalus 

 dauac was executed in the general manner of Schmidt's treatment, so 

 that their two papers are readily comparable. 



Several papers by R. J. Daniel have since appeared dealing with 

 the very complicated abdominal musculature of shrimps, but these 

 papers have little bearing upon the following study, because the shrimp 

 and the crab are structurally dissimilar in regard to their abdominal 

 organization. 



I am particularly indebted to R. E. Snodgrass, of the Bureau of 

 Entomology and Plant Quarantine (if the United States Department 

 of Agriculture, for his invaluable assistance and advice in interpreting, 

 describing, and figuring the muscles of the blue cral), and in comparing 

 them with those of other arthropods. 



I am likewise indebted to Prof. C. J. Pierson, of the Department of 

 Zoology of the University of Maryland, for many suggestions, and to 

 Dr. R. V. Truitt, of the same department, for directing my prelimi- 

 nary survey of other anatomical features of the blue crab. 



My sincere thanks are due also to Dr. Waldo L. Schmitt, curator 

 of the division of marine invertebrates of the United States National 

 Museum, for donating comparative material for dissection and for 

 making available much of the literature dealing with crustaceans. 



The work on the appendages of the blue crab was done in partial 

 fulfillment of the requirements for the degree of Doctor of Philosophy 

 at the University of Maryland. 



