106 FISHES. 



elements pass again partly into the Trigeminal, partly into the 

 Facial nerve. On the passage of these stems through the 

 skull (through a foramen or foramina in the ahsphenoid) they 

 form a ganglionic plexus, in which the palatine ramus and 

 the first stem of the Trigeminus generally possess discrete 

 ganglia. The branches which issue from the plexus and 

 belong exclusively to the Trigeminus, supply the organs and 

 integuments of the frontal, ophtlialmic, and nasal regions, and 

 the upper and lower jaws with their soft parts. The Facial 

 nerve supplies the muscles of the gill-cover and suspensorium, 

 and emits a strong branch accompanying the Meckelian car- 

 tilage to the symphysis, and another for the hyoid apparatus. 



The Ncrvus acusticus (eighth pair) is strong, and takes its 

 origin immediately behind, and in contact with, the last root 

 of the seventh pair. 



The Ncrvus glosso-pharyngeus {ninth pair) ^ takes its origin 

 between the roots of the eighth and tenth nerves, and issues 

 in Teleostei from the cranial cavity by a foramen of the 

 exoccipital. In the Cyclostomes and Lepidosiren it is part 

 of the jSTerATis vagus. It is distributed in the pharyngeal and 

 lingual regions, one branch supplying the first branchial arch. 

 After having left the cranial cavity it swells into a ganglion, 

 wliich in Teleostei is always in communication with the 

 sympathic nerve. 



The Ncrvus vagus or 2^neu7nogastricus {tenth pair) rises in 

 all Teleostei and Paheichthyes with two discrete strong roots : 

 the first constantly from the swellings of the corpora resti- 

 formia, be they thinner or thicker and overlying the sinus 

 rhomboidalis, or be they developed into lateral plaited pads, 

 as in Acipenser and Chondropterygians. The second much 

 thicker root rises from the lower tracts of the medulla oblon- 

 gata. Both stems leave the cranial cavity by a common fora- 



^ This nerve is not shown in the figiire of the brain of the Perch (Fig. 41), 

 as reproduced above from Cuvier. 



