Il8 NERVE COMPONENTS OF BONY FISHES. 



dorsal musculature running from the skull to the extra- 

 scapular (post-temporal) and supra-clavicular bones and 

 supplied by the first spinal nerves is not homologous with 

 the trapezius of selachians and Chimaera, but is a new 

 structure in the teleosts. On the latter point he is doubt- 

 less correct, /. e. , so far as the proper dorso-lateral muscu- 

 lature is concerned; but in Menidia the trapezius muscle 

 is present in the typical form in addition and receives the 

 typical innervation, so that Vetter's first statement will 

 require modification. The "trapezius" muscle described 

 by McMurrich ('84) in Amiurus is stated to be innervated 

 from the first spinal, so that it will fall under Vetter's 

 rule. In Lophius, however, the case is apparently the 

 same as in Menidia, for here the " humero-mastoid " 

 muscle is supplied by the vagus (Guitel, '91). 



Vetter regards the m. trapezius of selachians and 

 chimseroids as derived from the superficial " Ringsmuscu- 

 latur," or constrictor system. Its innervation from the 

 vagus accords with this. 



Max Fiirbringer ('97, p. 374) verifies the accounts of 

 Rohon, Dumeril and Owen that the caudal ascending 

 motor vagus root in Hexanchus is the accessorius Willisii. 

 He has traced its connection in this species with the m. 

 trapezius, which is especially well developed, and thus 

 demonstrates its homology with the accessorius. He con- 

 troverts the view of Stohr, Wiedersheim and others that 

 the XI is a descendant of spinal nerves ; but regards the 

 vago-accessorius as indigenous to the head, "a primordial 

 cranial nerve which has nothing to do with spinal nerves." 

 This seems probable anatomically but requires embryo- 

 logical confirmation. 



