XIII.] THE FROG. 1 



The tenth spinal nerve leaves the neural canal by t 

 coccygeal foramen, and is distributed to the adjacent parts 



Sympathetio. 



The sympathetic system consists of ten ganglia, connect 

 by longitudinal commissures, and situated on each side 

 the ventral face of the vertebral column; in the region 

 the dorsal aorta they come into close relation with it. Ea 

 sympathetic ganglion is joined by a communicating fi 

 ment with one of the spinal nerves, and the most anter 

 ganglia are united, in the same way, with the ganglion of t 

 ninth and tenth cerebral nerves. From this a delicate coi 

 which must be regarded as the most anterior part of t 

 sympathetic, passes into the cranial cavity, on the ini 

 side of the periotic capsule, and unites with the Gasseri 

 ganglion. 



The branches of the sympathetic accompany the vesse 

 and large branches are given to the viscera of t 

 abdomen. 



The Olfactory organs are two wide sacs which occupy 

 the space between the mesethmoid cartilage, the aiitorbi 

 processes, and the premaxUlffi and Inaxillae, and open in frc 

 and dorsaUy by the external nares, behind and ventra 

 by the posterior nares. The inner faces of these sacs 8 

 lined by a very peculiar epithelium, and the olfactory nerv 

 with some branches of the trigeminal, are distributed 

 them. 



The Eyeball is lodged in the orbit and protected by t 

 eyelids described above. It has four recti muscles whi 

 proceed from the inner wall of the orbit, and are attach 

 to the circumference of the globe; within these is ^retraci 



