i 7 6 



COMPARATIVE MORPHOLOGY OF VERTEBRATES. 



the medulla to the ganglion jugularis, beyond which the dorsal rami 

 arise and then the main trunk runs backward, giving off as many 

 branchial nerves as there are gill clefts, each with an epibranchial 

 ganglion and each dividing into pre- and post-trematic rami. To 

 this extent the tenth is a polymeric nerve with coalesced proximal 

 portions. 



Near the last cleft the main trunk divides into two nerves. One of 

 these, the ramus lateralis, continues back, just beneath the skin, to 

 innervate the lateral line organs of the trunk and tail. The other, the 



FIG. 174. Diagram of cranial nerves of a cat, the lower jaw reflected, after Mivart. 

 II-XII, cranial nerves; ct, chorda tympani; d, dentary nerve; g, Gasserian ganglion; io, 

 infraorbital nerve; /, lingual nerve; li, Is, laryngeus inferior and superior; md, mandibularis 

 nerve; mx, maxillaris nerve; o, ophthalmic nerve; t, tongue. 



ramus intestinalis, goes inward and backward to supply the cesoph- 

 agus, stomach, heart and other viscera (in air-breathing vertebrates the 

 lungs also, whence the name pneumogastric nerve). In the dorsal 

 rami and the branchial nerves the components are about the same as in 

 the ninth nerve. The most caudal of the motor roots of the vagus 

 furnish visceral motor fibres which go to some of the muscles connected 

 with the pectoral'arch and appendages, while others pass, by way of the 

 intestinalis, to the viscera. In the same way visceral sensory fibres go 

 through the same nerve to the taste buds of the pharynx, and in the 



