NERVOUS SYSTEM AND SENSE ORGANS OF AMIURUS. 455 



PLATE VI.— (Continued). 



of the labyrinth, in which the outlines of the asteriscus (as) and 

 sagitta (s) are shown resting on the macula acustica lagence cochlea; 

 and macula acustica sacculi. 



Fig. 8. — Is through the ductus endolymphaticus which connects the sacculi. 

 It lies in the entrance to the cavum sinus imparis whose osseous 

 roof here slopes downwards so as partly to close the entrance. 

 The sacculi communicates here with the lagence cochlea;. The 

 wall of the labyrinth below is attached to the crest separating 

 the foveae sacculi. The relative position of lagenar and saccular 

 branches of the auditory nerve is well seen. The right side of 

 the section is immediately behind the vagus foramen, and catches 

 the ampulla of the frontal semi-circular canal. 



Fig. 9. — Shows the section of the sacculi in front of the ductus endolym- 

 phaticus ; the anterior wall of the ductus is also attached to the 

 crest. The ventral surface of the medulla oblongata is separ- 

 ated from the labyrinth by a layer of adipose tissue. The solid 

 wall of the labyrinth in which the ductus sacculo-utricularis is 

 excavated stretches upwards and outwards along the thickened 

 exoccipital. 



Fig. 10. — Cuts the labyrinth immediately behind the ductus sacculo-utricu- 

 laris (dus). On the lateral wall of the utriculus is one of the 

 macula, neglectce. The crest separating the foveae sacculi is now 

 much wider. 



Fig. 11. — For the region of the brain in the section vide Fig. 3, PL V. The 

 utriculus is cut behind the recessus utriculi. The posterior divi- 

 sion of the auditory nerve with its interpolated ganglion-cells is 

 not yet subdivided into Rr. lagenae and sacculi. The anterior 

 tips of the sacculi are about to enter the small cavities in the 

 prootics which receive them ; they are surrounded by delicate 

 tubes of dura mater. 



