MYOLOGY 23 



practically all the muscles save the smaller ones of the 

 feet. When the nerve constituted a smaller branch of a 

 plexus, however, the intricacies of the latter were not 

 always followed. 



In working out the myology of Neotoma only those muscles 

 readily distinguishable have been included, and the micro- 

 scopic examination of many specimens to establish the 

 presence or absence of doubtful fibers was at no time con- 

 sidered. In the case of a number of vestigeal muscles it is 

 often extremely difficult to differentiate the few fibers 

 present from the tougher connective tissue (for instance, in 

 the manus), and different investigators would arrive at 

 varying conclusions. Hence, it was considered better to 

 adopt a conservative attitude and recognize only those 

 muscles regarding the presence of which there could be no 

 reasonable doubt. 



Myological dissections were made of three specimens of 

 each species of the three subgenera, so as to have a check 

 on those details which exhibit a tendency to vary. In 

 addition, certain muscles of a variable character and certain 

 nerves were investigated in additional specimens of both 

 Neotoma and Homodontomys. An examination was also 

 made of special features of Neotoma intermedia, N. micropus, 

 and A^. floridana rubida. 



In each case, the muscles of Neotoma (Homodontomys) 

 fuscipes macrotis are the ones described in the text, and 

 remarks are made upon the corresponding muscles of the 

 subgenera Neotoma and Teonoma only when these differ to an 

 appreciable extent. This course was followed solely because 

 specimens of Homodontomys happened to be available in 

 greater quantity. As the work progressed it was found 

 that from an anatomical standpoint this procedure hap- 

 pened to be the most desirable one. 



It is perhaps unnecessary to call attention to the fact 

 that the musculature of no two specimens is precisely the 



