2352.0" BEATRICE WHITESIDE 
In the membranous auditory organ of the frog the following 
parts can be distinguished: (fig. 1) the utriculus (utr.) with 
the sinus superior (st.swp.utr.) and posterior (s?.post.utr.), the 
recessus utriculi (rec.utr.), the three semicircular canals (ca.s.c.) 
with the ampullae (amp.), the sacculus (sac.) with the ductus 
(d.e.) and saccus endolymphaticus (s.e.), the pars neglecta 
(p.negl.), the pars basilaris (p.bas.), the lagena cochleae (lag.), 
and the tegumentum vasculosum (not visible in the figure.) 
The utriculus is irregularly cylindrical in form, with its long 
axis running horizontally from back to front. It is situated 
close to the median side of the bony labyrinth. On one side the 
utriculus passes into the recessus utriculi; on the other, into the 
narrow part of the sinus posterior. The three semicircular 
canals arise from the utriculus and each one is connected with 
this organ by two ends, the crus simplex and the crus ampullare 
(amp.), the former not being any wider than the canal itself, 
whereas the latter expands into an oval sac. The utriculus 
communicates with the sacculus through the foramen utriculo- 
sacculare and is connected at the latter’s circumference with the 
sacculus and the pars neglecta. According to Gaupp, thesacculus 
of the inner ear has the shape of an oval sac, and possesses four 
pouch-like enlargements, namely, the lagena, the pars basilaris, 
the pars neglecta, and the tegumentum vasculosum. The 
auditory nerve enters the labyrinth with its two branches, the 
ramus anterior (r.ant.) and the ramus posterior (r.post.). It 
ends in the three cristae acusticae of the ampullae and also in 
the macula recessus utriculi, the macula sacculi, the macula 
lagenae, the macula neglecta, and the papilla basilaris. Each of 
the three first-mentioned maculae is covered with a membrane, 
on which many lime crystals are deposited. At its upper median 
side the wall of the sacculus expands into the ductus endolym- 
phaticus (recessus labyrinthi, aequaeductus vestibuli). This 
structure is a very long and narrow canal which runs upwards 
median to the utriculus, and leaves the bony auditory capsule 
through a special aperture, the foramen endolymphaticum (aper- 
tura aequaeductus vestibuli). Inside the cranial cavity it 
widens (Hasse, ’73) into the large saccus endolymphaticus, 
ee 
