52 EDWARD L. RICE 
retained, and by that of E. Fischer (’01 b, 1903) on Talpa and 
Semnopithecus, Voit (09 b) on the rabbit, Olmstead (’11) on 
the dog, Macklin (714) and Kernan (’16) on human embryos, 
and Terry (17) on the cat, in all of which forms transitional 
stages were observed. In view of these discoveries, I believe that 
the lateral part of the membrane filling the. fenestra cochleae of 
stage 6 of Eumeces (corresponding to the filling of the lateral 
aperture of the recessus scalae tympani in Lacerta and stage 5 
of EKumeces) may be safely homologized with the secondary 
tympanic membrane of the mammal, while the median portion 
(corresponding to the filling of the median aperture) occupies 
the position of the aquaeductus cochleae of the mammal. I 
have been unable to demonstrate an actual connection here 
between the lymph spaces of the developing saccus perilym- 
phaticus and those of the cranial cavity, but such may well 
appear in later stages. 
Conditions in the region of the recessus scalae tympani are 
decidedly more complicated in the turtles (Gaupp, ’05 b; Nick, 
"12; Kunkel, ’12 b) than in the lizards. This is due in part to 
the different course of the glossopharyngeal nerve (described in 
the next paragraph) and in part to the presence of the problem- 
atical ‘ductus hypoperilymphaticus’ described by Nick and 
Kunkel. Versluys (98) has emphatically denied the homology 
of the fenestra cochleae or rotunda of the reptile with the foramen 
rotundum of the mammal. His argument has been considered 
somewhat fully by Gaupp (’00). In part, at least, the recognition 
for the mammal of the division of a primitive fenestra cochleae 
into definitive foramen rotundum and aquaeductus cochleae 
would remove the ground of difference. 
In this connection it is well to consider certain apparent 
anomalies in the course of the glossopharyngeal nerve in different 
reptilian forms. In the lizards (Versluys, ’98; Gaupp, ’00), 
Sphenodon (Schauinsland, ’00), and crocodiles (Parker, ’83, cited 
and confirmed by Gaupp, ’05 b and 711; Shino, 714) the course 
is ‘extracapsular’—1.e., the nerve leaves the skull through the 
fissura metotica, between the otic capsule and the basal plate. 
