100 EDWARD PHELPS ALLIS, JR. 



which I considered to be the persisting primitive aortic vessel 

 of the mandibular arch of that fish and hence the homologue 

 of the so-called afferent mandibular artery of my later descriptions 

 of the Selachii. There was thus evidently some error of obser- 

 vation somewhere in these several works, or actually differing 

 conditions which needed explanation, 



Mr. Henry's drawings and dissections were first controlled, 

 and, as they were found to be correct, he was instructed to control 

 the relations of the artery to the nerve in Amia; where he found 

 them, both in embryos and the adult, as given in my earlier work. 

 He then also found the same relations of artery to nerve in young 

 specimens of Cottus aspera that had been sectioned, in the adult 

 of Scorpaena scrofa, and in an 80 mm. specimen of Lepidosteus. 

 It was thus probable that in both embryos and adults of all the 

 Teleostei and Holostei the so-called arteria hyoidea lay external 

 to the nervus mandibularis internus facialis, as it is evident that 

 the primitive aortic vessel of the mandibular arch naturally 

 should. Sections of 36 mm. and 55 mm. embryos of Mustelus 

 vulgaris were then examined, and there also the artery was found 

 to lie external to the nerve. It accordingly seemed quite certain 

 that the so-called afferent mandibular artery of my several 

 descriptions of the adult selachian could not be the persisting 

 primitive aortic vessel of the mandibular arch; for that this 

 arterial vessel of Mustelus could have changed its relations to 

 an important branch of the nervus facialis, from external to 

 internal, after passing the age represented by a 55 mm. embryo, 

 I considered wholly improbable. 



In my work on Chlamydoselachus I had found a long but deli- 

 cate branch of the so-called afferent mandibular artery which 

 lay external to and approximately parallel to the latter artery. 

 Its relations to the nerves and muscles of the region, which I 

 at the time considered of no great morphological significance, 

 had not been noted, but the artery was said (Allis, '11 b, p. 516) 

 to run upward in the hyal arch, to supply the muscles of the 

 region, and apparently to represent the anterior efferent 

 artery of the hyal arch. In Mustelus, Mr. Henry had also found 

 a very small artery which had an approximately similar course. 



