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Nachdruck verboten. 



The Pseudobranchial and Carotid Arteries in Chlamydoselachus 



anguineus. 



By Edward Phblps Allis jr., Menton. 

 With 2 Figures. 



In 1889 Ayers, in a work entitled "The Morphology of the 

 Carotids", described the branchial and carotid arteries in Chlanaydo- 

 selachus, and these arteries, as described by him, were in certain re- 

 spects quite unusual. Ayers himself called especial attention to this 

 fact, and on the conditions, as described by him, he based certain 

 quite important conclusions. In 1908 I had occasion to consult this 

 work by Ayeks, and I then published (Allis, 1908) a diagrammatic 

 representation of the carotid and related arteries in this fish, as de- 

 scribed by Ayers but as interpreted by myself. The diagram was, 

 however, most unsatisfactory, and having since received several heads 

 of this fish, most kindly sent me by Prof. Bashford Dean, I have 

 had dissections made of the arteries concerned, in two of them, the dis- 

 sections being prepared by my assistant, Mr. Jujiro Nomura. The 

 arteries, as I find them, are shown in the accompanying Figure 1, the 

 dorsal aorta being swung upward and the truncus arteriosus downward, 

 so as to bring the vessels all into the same plane. In Figure 2 a dia- 

 grammatic representation of the same arteries is given, for comparison 

 with the diagrams given in my other works on this same subject. 



In both of my specimens the truncus arteriosus bifurcates ante- 

 riorly, and each vessel so arising separates into two parts, one of 

 which is the afferent artery of the hyoidean arch, and the other the 

 afferent artery of the first branchial arch. Posterior to this the afferent 

 arteries of the second, third, fourth and fifth branchial arches arise 

 successively and independently from the truncus; this all being wholly 

 in accord with Ayers' descriptions. But on both sides of the second 

 and larger one of my two specimens, which alone was carefully ex- 

 amined in this respect, the several afferent branchial arteries, ex- 

 cepting only the fifth one, are not single throughout their entire length, 

 as Ayers has shown- them; each of the first four branchial arteries 



