485 



evidently being a vertebral artery. Posterior to this latter artery, 

 three other and more important arteries arise on either side from that 

 portion of the median dorsal aorta that lies anterior to the glosso- 

 pharyngeus efferent arteries, the roots of these arteries being shown 

 in my figure of the arteries of this fish. From the posterior one of 

 these three arteries a large branch is sent into the spinal canal, accom- 

 panying one of the spinal nerves, and there falls into the myelonal 

 artery. From the other two arteries no branch could be traced into 

 the spinal canal, but they are nevertheless quite certainly vertebral 



om peer ec epsb 



psö 



amd 



aaff 



cor 



Fig. 1. Branchial, pseudobranchial and carotid arteries in Heptanchus cinereus; 

 the dorsal aorta swung upward and the truncus arteriosus downward so as to bring 

 the vessels all into the same plane. 



aa I. II. etc. afferent arteries in the 1st, 2nd, etc. branchial arches; a. cer. 

 anterior cerebral artery; ahy afferent hyoidean artery; aynd afferent mandibular 

 artery; apsb afferent pseudobranchial artery; ch choroid gland; cor coronary artery; 

 da dorsal aorta; ea. I. II. etc. efferent arteries in the 1st, 2nd, etc. branchial arches; 

 ec external carotid; ehy efferent hyoidean artery; ei)sb efferent pseudobranchial artery; 

 ic internal carotid ; ilh internal lateral hypobranchial artery ; Ida lateral dorsal aorta ; 

 om ophthalmica magna artery; op optic artery; p. cer posterior cerebral artery; psb 

 pseudobranch ; s. ahy secondary afferent hyoidean artery ; ta truncus arteriosus. 



arteries. As these several arteries follow^ each other in what seems 

 to be serial order, and as the two anterior ones both perforate 



