THE SO-CALLED MANDIBULAR ARTERY AND THE 



PERSISTING REMNANT OF THE MANDIBULAR 



AORTIC ARCH IN THE ADULT SELACHIAN 



EDWARD PHELPS ALLIS, Jr. 



Menton, France 



TWO FIGURES 



In connection with my recent work (Allis, '15) on ''the homolo- 

 gies of the hyomandibula of the gnathostome fishes" I frequently 

 had to consult drawings of dissections, made during the summer 

 of 1914 by my assistant, Mr. John Henry, of the adult Heptan- 

 chus cinereus- and the adult Mustelus (probably vulgaris). 

 These dissections had been made with special reference to a 

 study of the ligaments related to the mandibular and hyal 

 arches, and I particularly wished to know the relations of these 

 ligaments to the so-called afferent mandibular artery of my sev- 

 eral works on the Selachii. This latter artery I considered to be 

 the persisting primitive aortic vessel of the mandibular arch, and 

 it was to be traced upward, if possible, to its assumed connection 

 with the definitive afferent pseudobranchial artery, this con- 

 nection not having been found in any of the dissections made in 

 connection with my earlier works relating to this subject (Allis, 

 'lib, '12b). 



In Heptanchus this connection was, again, not found, but it was 

 found in Mustelus, and I noticed that, in the drawings relating to 

 this latter fish, the nervus mandibularis internus facialis ran 

 downward and forward, external to the so-called afferent man- 

 dibular artery. That a branch of the posttrematic nerve of the 

 hyal arch, a branch distributed to the inner surface of the man- 

 dible, could lie external to the primitive aortic vessel of the 

 mandibular arch seemed, in itself, highly improbable. Further- 

 more, I had several years before, in Amia (Allis, '00, p. 114), 

 found this nerve lying internal to the so-called arteria hyoidea, 



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