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The appendicular muscles of Necturus maculosus.. 



By 



Harris Hawthorne Wilder, 



Professor of Zoology in Smith College, Northampton, Mass., U. S. A. 

 With Plates 23-27. 



Problems relating to the origin of the band type of Vertebrate 

 limb (Chiridium), especially that of its separate parts, are rendered 

 extremely difficult from tbe outset through the failure of the usual 

 records lipon which we are aecustomed to rely; the adult anatomy 

 of the lower forms, and the earlier developmental stages in the 

 higher. The earlier forms of Vertebrates with a chiridial appendage 

 have been entirely lost, and thus far, with the exception of a few 

 slight indications, palaeontology is equally silent in the matter. 

 Nor does embryology furnish much more, for it is well-known that, 

 owing to the greatly accelerated development of these parts in all 

 the higher Vertebrates, the earlier stages are either dropped out 

 altogether or are hastened over so rapidly, and with so little atten- 

 tion to details that the cells of which the limb-buds are composed 

 are seen to arrange themselves from the outset into the form of 

 the adult organs, and give few indications of the earlier conditions. 



It becomes thus of the greatest importance to investigate care- 

 fully and put on record the anatomical details of the adult limbs 

 in the lowest tetrapod Vertebrates we still possess, and in this 

 connection the lower Urodeles are seen to be of first importance. 

 Here again, however, the fate investing the early history of the 



