400 THE SKIN AND THE SENSE-ORGANS. 



(saccits endolymphaticus), placed between the brain and cranium. 

 The sac is very vascular and contains crystalline otoliths. 



(7) The pars neglecta (Figs. 247, 248, 249) was described by 

 Hasse as the 'first part of the cochlea' (' Anfangstheil der Schnecke'), 

 but according- to Retzius it does not belong to the cochlea. It is 

 placed above and in front of the pars basilaris cochleae, above and a 

 little behind the lagena cochleae, therefore above the upper and pos- 

 terior part of the saccule, and under the middle part of the utricle. 

 It is really a prolongation of the saccule, with which it communi- 

 cates by an elongated oval opening placed externally and immedi- 

 ately below the opening of the canalis utriculo-saccularis. It is an 

 oval vesicle, with its roof intimately united with the lower wall of 

 the utricle; anteriorly it is broad, posteriorly narrowed. The 

 macula acusiica neglecta is attached to the roof of the vesicle and 

 consists of an anterior heart-shaped and a posterior semilunar 

 portion united by a narrow connecting piece (Fig. 250 III and VII), 

 The ramulus neglectus divides into two branches, which supply the 

 two parts of the macula. On the macula acustica neglecta rests the 

 membrana tectoria (Deiters) ; the membrane is S-shaped, with the 

 anterior end narrow, the posterior broad (Fig. 250 VII) ; the borders of 

 the membrane are pierced by numerous small round holes, the central 

 part has smaller and fewer perforations, and is finely striated. 

 From the middle of the posterior part of the upper surface a thicker 

 portion projects downwards into the cavity of the pars neglecta ; it 

 has a narrow, deep notch for the nerve at about its middle ; ante- 

 riorly it points towards a sickle-shaped piece, which is curved in- 

 wards. Canals run obliquely downwards and inwards from the 

 apertures on the superior surface.- The membrane is clear, homo- 

 geneous, partly finely striated, and corresponds with the membrana 

 tectoria of the pars basilaris, etc. 



(8) The lagena cochleae (Figs. 247, 248, and 249 1} is an oval 

 swelling of the membranous labyrinth ; it lies close to the sacculus 

 with its broader end forwards, the narrower directed backwards. 

 By a large rounded opening at the posterior end it communicates 

 with the saccule by means of a rounded space common to the lagena 

 cochleae and the cochlea. The papilla acustica lagenae (pi] is situated 

 in the posterior wall of the lagena it is elongated, oval, and supplied 

 by the ram. lagenae. The papilla is covered by a plate-like otolith 

 formed of numerous rounded particles. 



(9) The pars basilaris cochleae (Figs. 247, 248, and 249 pb} is 

 placed on the posterior thickened wall of the saccule and lies above 



