64-2 ME FRANK J. COLE ON THE 



he found the ventral section of the infra-orbital canal, instead of being connected with 

 the hyomandibular, coming from the dorsal section of the infra-orbital, the latter canal 

 therefore consisting in this specimen of a dichotomised trunk instead of two separate 

 divisions. G-arman further states that the oral and jugular canals may be traced across 

 the chin to meet their fellows of the opposite side in a series of dots and splashes. This 

 is interesting when we remember that these traces are represented by functional canals 

 in Harriotta. 



Garman points to a resemblance between the geography of the lateral line system of 

 Holocephali and Sharks ; but I do not think the resemblance is more than one of kind. 

 It is extraordinary what a fundamental resemblance there is to be seen in the lateral 

 line system of all Fishes. Compare in this connection the memoirs of Allis and Ewart 

 (49 and 58). Allis, by the way, considers the canals supplied by the glossopharyngeal 

 and lateralis to belong to the infra-orbital system, which I take to be a confirmation of 

 my view of the unity of all the different parts of the system. 



One more observation on the anatomy of the sensory canals. These are in a semi- 

 closed condition both anteriorly and posteriorly, owing to the presence of large numbers 

 of imperfect calcified rings. On decalcification the lips of the canals immediately begin 

 to gape. Anteriorly the approximation of the lips is more marked, and there occur at 

 intervals numerous diamond-shaped openings. These openings indicate the position of 

 the sense organs, which are situated midway between them, and the same number of 

 openings occurs on both sides. See fig. 1. 



THE CRANIAL NERVES OF CHIMERA. 



E. The Eye Muscle Nerves. 



Having nothing new to describe in respect to the olfactory and optic nerves, I shall 

 commence my description of the cranial nerves with the Illrd. 



The Oculo-motor, or Third cranial nerve. — This large nerve arises by two roots from 

 the crus cerebri at the anterior termination of the latter just behind the pituitary body. 

 It courses forwards and slightly downwards at the side of the pituitary body towards 

 its foramen, which it enters as an undivided nerve. On emerging into the orbit it 

 immediately gives off a branch to the superior rectus muscle of the eye, and at the 

 same time bifurcates into nerves of about equal size. These two branches I shall 

 describe as the dorsal and ventral rami of the oculo-motor, and they run respectively 

 over and under the optic nerve. The former courses straight across the orbit dorsal to 

 the inferior rectus and inferior oblique, and fans out on the internal rectus* ; whilst the 

 latter, after giving off a branch to the inferior rectus, pursues a somewhat parallel course, 

 and supplies the inferior oblique. 



* Rectus medialis of Schwalbe (23). 



