RATA. 
323 
The auditory nerve is simple and short and passes to 
the auditory capsule. 
If the jugular sinus be cut 
open throughout its length 
the glossopharyngeal ( IX.) 
and vagus (X.) nerves will 
easily be exposed. The 1Xth 
is simple and passes from 
behind the auditory capsule 
to the first gill-slit. 
The vagus (X.) has four 
branchial branches to the 
four last gill-slits, a Ja¢eral 
Zine branch under the skin 
and a wrsceral branch which 
passes to the heart and 
stomach. 
The spinal cord gives 
off paired spinal nerves, the 
first fifteen (or 15 to 18) of 
Fig. 230.— THE Ear (Mrem- 
BRANOUS LABYRINTH) OF THE 
SKATE (Diagrammatic). 
Semi-circular Canal. 
\ 
Utriculus, 
Horizontal 
Semi-circular 
Canal. 
Sacculus, 
Note that there is no middle or outer 
ear, and that the inner ear communicates 
by a duct to the exterior, 
which join together to form the brachial plexus, passing to 
the pectoral fin. 
We may summarise the cranial nerves as follows :— 
FORE-BRAIN. 
I. Olfactory. 
II. Optic. 
MID-BRAIN. 
III. Oculomotor. 
IV. Trochlear. 
HIND BRAIN. 
V. Trigeminal. 
1. Part of ophthalmicus tke 
superficialis. 
2, Ophthalmicus profun- | 2 
dus. 3. Outer buccal,* 
3. Maxillary. 4. 
4. Mandibular. 5. Palatine 
VI. Abducens. 
VII. Facial. 
Part of ophthalmicus 
superficialis. 
. Hyomandibular. 
Inner buccal.t 
spiracular). 
VIII. Auditory. 
IX. Glossopharyngeal. 
X. Vagus. 
1. Four branchials, 
2. Lateral line. 
(and  pre- 
3. Visceral. 
* The branches in ifa/ic type disappear in Vertebrata above the fishes, besides 
parts of other branches. 
+ The maxillary anast--moses to some extent with the inner buccal herve, but 
whether fibres of V. actually supply the ampulla at the termination of the inner 
buccal is doubtful. 
