1894-5.] Cranial and Spinal Nerves of Elasmobranelis. 475 
On the Dorsal Branches of the Cranial and Spinal Nerves 
of Elasmobranchs. By J. C. Ewart, M.D., F.R.S., 
Eegius Professor of Natural History, and P. J. Cole, Zoological 
Department, University, Edinhurgli, 
(Read March 18, 1895.) 
The Cranial Nerves. 
I. The Glossopharyngeal . — The glossopharyngeal is usually looked 
upon as the most typical of the cranial nerves. In Amia, according 
to Allis,* it consists of post- and prse-hranchial branches, a visceral 
or pharyngeal branch, and a dorsal branch which takes part in 
innervating the lateral line system — supplying by a single twig 
one of the sense organs of the lateral canal, and in addition a row of 
pit organs. Hitherto a branch of the IX has not been found passing 
to any of the lateral sense organs in Elasmobranchs. In a paper on 
the Lateral sense organs of Elasmobranchs,! the IX nerve was traced 
to the skin over the auditory region, but no branch was found passing 
to any of the sense organs. It was, however, subsequently found 
supplying one or more of the sense organs immediately in front of 
the most anterior organs supplied by the lateralis nerve. Collinge, 
in a recent paper “ On the Sensory Canal System of Fishes,”.]: says : 
— “ Ewart has suggested that possibly the most anterior portion of 
the lateralis canal may be innervated by nerve fibres from the glosso- 
pharyngeal nerve previous to its leaving the cranial cavity. So far, 
he has failed in Loemargus to find any branches which pass to either 
the sensory or ampullary canals from this nerve. In Polyodon I 
have met with similar results, the anterior portion of the lateral 
canal being innervated by a branch of the vagus.” Recently we 
have found that, as in Amia, the glossopharyngeal sends branches to 
the lateral sense organs. In a specimen of Lcemargus, which had 
* “ Anat. and Devel. of the Lateral Line System in calva,” Jour. 
Morph., vol. ii. 
t J. C. Ewart, “ Sensory Canals of Lcemargus,'' Trans. Boy. Soc. EcUn., 
vol. xxxvii. p. 78. 
X “ Sensory Canal System of Fishes ” (Ganoids), Quart. Jour, of Mic. Sci., 
vol. xxxvi. p. 519. 
